City  Roads  and  Pavements 

SUITED  FOR   CITIES   OF   MODERATE    SIZE 

BY 

WILLIAM  P1ERSON  JUDSON,  M.  Am.  Soc.  C.  E. 


Containing  well  illustrated  and  up-to-date  descriptions  of 
the  various  kinds  of  pavements  in  practical  use,  with 
costs  of  laying  and  maintenance  and  many  statistics 
for  cities  and  localities  all  over  the  United  States,  and 
references  to  European  practice  and  experience. 


THIRD  EDITION,  REVISED  AND  ENLARGED 

Cloth,  6X9  inches.      197  pages.      69  illustrations. 
Price,  $2.00  net. 


THE  ENGINEERING  NEWS  PUBLISHING  COMPANY 


ROAD  PRESERVATION 


AND 


DUST  PREVENTION 


BY 

WILLIAM  PIERSON  JUDSON 

^» 

Consulting  Engineer 

Member  of  the  American  Society  of  Civil  Engineers 
Member  of  the  Institution  of  Civil  Engineers  (of  Great  Britain) 

Member  of  the  Massachusetts  Highway  Association 

Member  of  the  American  Society  of  Municipal  Improvements 

Author  of  "  City  Roads  and  Pavements  " 


NEW  YORK 
The  Engineering  News  Publishing  Co. 


LONDON 
Archibald  Constable  &  Co.,  Ltd. 

1908 


Copyright,  1908, 

BY 

THE    ENGINEERING    NEWS  PUBLISHING   COMPANY. 


Entered  at  Stationers'  Hall,  London,  E.  C. 


TABLE   OF   CONTENTS. 


ROAD  DUST— ITS  CONTROL  AND  PREVENTION— 

Origin.  Limestone  dust.  Motor-car  effects,  as  stated  by 
Institution  of  Civil  Engineers  (of  Great  Britain);  by  the  U.  S. 
Office  of  Public  Roads;  by  the  Massachusetts  Highway  Com- 
mission; by  the  Massachusetts  Highway  Association;  by  the 
Department  of  Roads  and  Bridges  of  France.  Need  of  Mainte- 
nance. Conditions,  and  methods  of  prevention,  in  England; 
in  France;  in  the  United  States,  (i  illustration)  Page  9 

MOISTURE— 

Water  as  a  dust  preventive.  Sea-water.  Calcium  chloride: 
origin;  methods  of  use;  details;  results;  cost.  Akonia. 
Lymanite.  Fitzsimmons  patent  dust-layer.  Conclusions: 

Page  i 8 

OIL  EMULSIONS— 

Summary.  Various  oils  used.  Objections.  Methods:  Cook's 
emulsion;  Westrumite,  in  England,  in  United  States,  in  France, 
and  in  Germany.  Westrumite  2.  Pine-oiline.  Coudrogenit. 
Apulvite.  Sandisize.  Crompoid  D.  Dustoline.  Terracolia. 
Pulvicide.  Ermenite.  Hahnite.  Rapidite.  Mechanical 
emulsifier.  Conclusions.  Page  24 

OILS— 

Summary.  Crude  petroleums:  of  the  United  States,  Pennsyl- 
vania, Ohio,  California,  Texas,  Kentucky,  Indian  Territory; 
of  Russia;  of  Austria;  of  Borneo.  Residual.  Asphaltic. 

3 

265947 


TABLE   OF   CONTENTS. 

Slow  distillation.  Pipe  line  for  California  oil.  Causes  of 
failures.  History:  first  use.  Oil  on  stone  roads:  at  Cranston, 
R.  I.;  at  Liverpool,  England;  at  Sidney,  Australia;  at  Jackson, 
Tenn.;  at  Pasadena,  Cal.;  at  Bayonne,  N.  J.;  at  Chicago, 
111.;  at  Beverly,  Mass.;  at  Newton,  Mass.;  New  York.  Oiled 
earth  and  sand  roads:  in  California;  in  Eastern  States.  Sub- 
stitutes for  California  asphaltic  oils.  Methods:  petrolithic; 
rolling  tamper.  Cheap  rural  oiled  roads.  Oiled  gravel  roads. 
Oiled  broken-stone  roads.  Repairs  of  oiled  roads.  Asphalt- 
oilene.  Asphaltine.  (i  illustration)  Page  37 

COAL-TAR  PREPARATIONS— 

Summary.  Refined  tar:  Heating-kettles;  uniformity.  Opin- 
ions: of  Massachusetts  Highway  Commission;  of  Thos.  Aitken, 
M.  I.  C.  E.;  of  French  road  engineers;  of  Logan  Waller  Page; 
of  Charles  W.  Ross.  Methods:  Success  dependent  upon  four 
conditions.  Failures  and  their  reasons.  History.  Tar-spray- 
ing machines:  competitive  trials.  Quality:  Importance;  charac- 
teristics; tests;  uniformity.  Tarvia  "A."  Clare's  patent  Tar- 
Compo.  Methods:  Cleaning  and  scraping;  heating;  spreading; 
covering;  finishing;  cost.  Tarvia  "B,"  or  cold  treatment: 
Sprinkling;  cost.  Tarvia  on  Massachusetts  roads ;  in  parks;  at 
Lynn;  at  Wayland;  at  Newton.  Penetration.  On  Rhode 
Island  roads:  at  Tiverton.  Conclusions.  Appliances: 
"  White "  machine.  (8  illustrations)  Page  63 

TAR-SPRAYING  MACHINES— 

"Aitken's  patent  pneumatic  tar-sprayer":  description;  method; 
on  new  macadam;  cost;  use  on  old  surface;  details;  cost. 
The  "Tarspra":  description;  method.  " Lassailly-Johnston 
patent  tar  road-binder":  description;  method;  results  in 
France  and  England.  "Thwaite  anti-road-dust  machine": 
description;  method;  cost.  "  Tarmaciser " :  description; 
method.  Conclusions.  Page  89 

TAR-MACADAM— 

Summary.  Various  forms.  History.  Hand  mixing.  Ma- 
chine mixing.  Methods  in  England:  at  Grimsby;  at  Notting- 
ham; at  Gainsborough.  Tarmac:  at  Newark,  England; 


TABLE   OF  CONTENTS. 

objections;  methods;  extent  of  use;  comparative  costs.  Tarred 
crushed  stone:  kinds  of  rock;  methods;  surfacing  old  roads; 
poor  method;  comparative  costs  at  seven  places  in  England. 
The  " Gladwell "  system :  summary;  methods;  cost;  opinions. 
Tar-macadam  in  United  States  and  Canada:  summary; 
opinion.  Methods  and  costs:  in  Rhode  Island;  in  Canada. 
Comparative  costs  in  Massachusetts;  improved  methods. 

Page  98 
ROCK-ASPHALT  MACADAM.— 

Summary.  Sources  of  supply.  Limitations  of  use.  Methods : 
in  Little  Rock,  Arkansas;  details;  cost.  In  Bowling  Green, 
Kentucky;  description  of  material;  methods;  results;  cost. 
Use  in  "Gladwell"  system.  Sheet  rock-asphalt;  methods;  cost. 
Binder  for  macadam.  Page  121 

BITULITHIC  PAVEMENT— 

Summary.  Characteristics.  Opinions:  of  George  W.  Tillson, 
President  of  American  Society  of  Municipal  Improvements;  of 
Massachusetts  Highway  Commission;  of  Chicago  South  Park 
Commission;  expressed  in  the  1902  and  the  1906  editions  of 
"City  Roads  and  Pavements."  History:  growth;  extent; 
imitations;  methods;  Semiportable  paving  plants;  descrip- 
tion; views  and  key/  Cost.  (6  illustrations)  Page  127 

INDEX  ..................     Page  137 


PREFACE. 


THE  preservation  of  surface  and  the  prevention  of 
dust  on  macadamized  roads  form  the  problem  now  to 
be  solved  by  engineers  charged  with  the  maintenance  of 
the  many  thousands  of  miles  of  broken-stone  roads 
which  have  been  built  throughout  Europe  during  the 
past  century,  and  in  certain  of  the  United  States  during 
the  past  decade. 

During  1906,  with  the  increased  use  of  motor-cars, 
this  problem  became  acute,  and  in  1908  it  is  conceded 
to  be  a  matter  of  prompt  betterment,  or  general  destruc- 
tion, of  costly  highways. 

This  implies  that  new  roads  proposed  and  in  progress 
must  be  better  built  than  the  old  ones;  that  they  must 
be  better  bonded  and  surfaced;  and  that  these  results 
must  be  reached,  if  possible,  without  unduly  increasing 
the  cost. 

Preservation  of  existing  roads  and  dust  prevention  on 
them  are  the  matters  which  are  most  urgent,  and  road- 
builders  have  been  working  and  experimenting  to  these 
ends  with  results  which  are  here  shown ;  including  the  ob- 
servations and  conclusions  of  the  writer  who  is  indebted 
for  many  of  the  details  to  the  engineers  of  the  works 
named,  as  well  as  to  the  engineering  publications  of  the 
United  States  and  of  Europe,  among  which  are :  the  Engi- 


PREFACE. 

neering  News,  the  Engineering  Record,  the  Good  Roads 
Magazine,  the  Municipal  Journal  and  Engineer,  and  the 
American  Gas-light  Journal,  all  of  New  York;  Municipal 
Engineering  of  Indianapolis;  Engineering-Contracting 
of  Chicago;  The  Engineer,  the  Surveyor  and  Municipal 
and  County  Engineer,  and  the  Journal  of  Gas-lighting 
of  London;  The  Journal  Fuer  Gasbeleuchtung  of  Berlin; 
the  publications  and  records  of  the  U.  S.  Office  of  Public 
Roads,  at  Washington;  the  reports  of  the  State  Highway 
Departments  of  New  York,  Massachusetts,  New  Jersey, 
Connecticut,  and  Rhode  Island;  the  report  of  the  Chief 
of  the  U.  S.  Corps  of  Engineers;  the  Annals  des  Fonts  et 
Chausses  of  France;  and  especially  the  Minutes  of  the 
Institution  of  Civil  Engineers  of  Great  Britain;  the 
Proceedings  of  the  American  Society  of  Civil  Engineers; 
the  Journal  of  the  Massachusetts  Highway  Association 
(as  well  as  its  informal  but  valuable  discussions) ;  and 
the  Proceedings  of  the  American  Society  of  Municipal 
Improvements.  The  general  estimate  of  the  importance 
of  the  subject  is  indicated  by  the  extent  of  its  discussions 
in  these  and  many  other  publications. 

WM.  P.  J. 

OSWEGO,  New  York, 
July  i,  1908. 


8 


ROAD    PRESERVATION   AND 
DUST    PREVENTION. 


ROAD    DUST:    ITS    CONTROL   AND 
PREVENTION. 


Dust  has  always  been  a  feature  of  broken-stone  roads, 
being  at  the  same  time  the  result  of  use  and  a  check 
upon  excessive  wear.  Whenever  the  surface  becomes 
free  from  dust,  by  wind  effect  or  otherwise,  it  has 
been  necessary  to  spread  a  thin  layer  of  sand  or  screen- 
ings, or  other  fine  material,  as  a  protection  to  the  stone- 
fragments  forming  the  road,  and  to  prevent  them  from 
" ravelling"  or  losing  their  bond.  When  these  stones 
or  the  screenings  forming  the  protective  layer,  or  both, 
have  consisted  of  limestone,  the  resulting  impalpable 
dust  has  always  been  most  objectionable  and  in 
many  cases  has  been  considered  intolerable,  both 
to  people  driving  upon  the  road  and  especially  to 
those  living  along  it.  When  this  limestone  dust  is 
wet,  the  resulting  mud  is  the  most  slippery  and  dan- 
gerous for  rubber-tired  wheels,  causing  more  side- 
slip than  any  other  material  used  for  roads. 


:  &OApLP£ESERVA.TION  AND  DUST  PREVENTION, 


MOTOR-CAR   EFFECTS. 

In  1905,  when  motor-cars  became  common,  the  rais- 
ing and  scattering  of  road-dust  increased  greatly,  and 
in  the  summer  of  1906  when  motor-cars  became  very 
numerous  both  in  Europe  and  in  the  United  States, 
the  subject  at  once  became  acute,  and  road-builders 
everywhere  found  that  a  new  condition  had  suddenly  de- 
veloped (particularly  on  those  macadam  roads  radiating 
from  the  cities  where  motor-cars  were  most  used),  and 
that  the  preservation  of  the  roads  demanded  that  a 
better  and  more  enduring  surface  be  made,  and  one 
that  will  neither  require  nor  produce  the  loose  sur- 
face layer  which  has  heretofore  been  a  necessary 
feature. 

In  England. — In  the  Minutes  of  Proceedings  of  the 
Institution  of  Civil  Engineers  (of  Great  Britain)  for 
September,  1906,  it  is  said: 

"Experience  has  proved  that  the  broad  pneumatic  tires  of  heavy 
motor-cars  at  high  speed  draw  out  small  particles  which  bind  the 
material  of  a  macadamized  road.  On  the  main  roads  (of  England) 
more  than  half  the  traffic  is  of  motor-cars,  which  may  reasonably  be 
expected  to  become  a  more  and  more  popular  means  of  travel,  to 
which  the  roads  must  now  be  adapted  by  introducing  into  them 
some  material  which  would  make  them  dustless;  for  which  pur- 
pose, tar,  or  some  tar  derivative,  is  the  only  remedy  now  in  sight. 
Motors  have  come  to  stay,  and  the  road-builders  mean  to  make 
the  roads  fit  to  carry  them.  The  estimated  cost  of  this  on  the 
main  rural  roads  of  England  and  Wales  is  put  at  eighty  million 
pounds  and  of  the  district  roads  outside  the  main  roads  at  184 
million  pounds.  (A  total  of  one  and  one-third  billion  dollars.) 

In  the  United  States. — That  this  condition  equally  con- 
cerns the  road-builders  of  the  United  States  is  shown  in 

10 


ROAD   DUST. 

the    1907   report  of  Logan  W.    Page,    Director  of   the 
U.  S.  Office  of  Public  Roads,  in  which  he  says: 

"In  recent  years  perhaps  the  most  important  and  certainly  the 
most  difficult  problem  which  has  engaged  the  attention  of  highway 
engineers  is  the  prevention  of  dust.  Until  the  general  introduction 
of  motor  vehicles,  dust  was  considered  as  neither  more  nor  less 
than  a  nuisance.  The  problem  has  now,  however,  assumed  a  more 
serious  aspect.  The  existence  of  our  macadam  roads  depends 
upon  the  retention  of  the  road-dust  formed  by  the  wearing  of  the 
surface.  But  the  action  of  rubber-tired  motor-cars  moving  at 
high  speed  soon  strips  the  macadam  road  of  all  fine  material,  the 
result  being  that  the  road  soon  disintegrates.  .  .  .  This  is  a  sub- 
ject which  should  engage  the  earnest  attention  of  the  National 
Government  at  once.  No  matter  how  important  we  may  deem  the 
building  of  good  roads,  we  cannot  but  consider  it  even  more  im- 
portant to  preserve  those  which  have  already  been  constructed." 

James  Owen,  M.  Am.  Soc.  C.  E.,  one  of  the  most 
experienced  of  American  road-engineers,  in  an  able 
paper  on  "Highway  Construction,"  before  the  1906 
meeting  of  the  American  Society  of  Municipal  Improve- 
ments, said: 

"Every  system  of  road  construction  should  be  immediately 
supplemented  by  a  maintenance  organization,  for  in  time  the  con- 
struction department  disappears,  but  the  maintenance  department 
is  permanent,  and  is  the  vital  point  in  the  future  road-development 
of  the  country.  .  .  .  The  automobile  is  demanding  attention  from 
engineers  as  to  whether  there  should  not  be  new  means  and  methods 
for  road  maintenance." 

At  the  annual  meeting  of  the  American  Road-makers' 
Association  on  March,  12,  1907.  Wm.  E.  McClintock, 
chairman  of  the  Massachusetts  Highway  Commission,  said : 

"We  have  a  new  problem  within  the  last  six  months,  which  is  that 
of  the  destruction  of  the  stone  road  by  the  automobile.  The  surface 
is  denuded,  the  fine  stone  thrown  off,  and  our  commission  is  strug- 

11 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

gling  with  the  problem  in  the  hope  of  finding  some  method  to  stop 
the  ravelling,  and  also  to  prevent  the  tremendous  dust  which  follows 
the  motor-car." 


DANGER   FROM   DUST. 

The  London  Lancet  of  July,  1907,  refers  to  this  road- 
dust  as 

"This  great  modern  plague  which  is  a  menace  to  health." 

The  Paris  Revue  Scientifique,  says: 

"  Street-dust  is  a  menace  to  health  of  the  gravest  character,  and 
is  a  matter  of  life  and  death." 


THE  DUST  NUISANCE 

Not  only  does  the  demand  for  relief  come  from 
recognized  authorities  and  from  the  road-users,  but 
also  from  the  property  owners  who  live  along  the 
roads,  and  pay  for  them,  and  who  find  that  the 

12 


ROAD    DUST. 

former  dust  to  which  they  had  objected  has  become  an 
hundred  fold  worse  and  not  to  be  endured;  especially  in 
England,  country  residences  which  have  long  been  desir- 
able and  valuable,  have  suddenly  become  neither  tenable 
nor  saleable,  and  others  have  been  sold  for  half  their  cost 
because  of  the  dust  from  adjacent  roads.  In  Massachu- 
setts, passing  motor-cars  have  even  thrown  up  fragments 
of  road-stones  into  the  windows  of  houses. 


CHANGE  IN  METHODS. 

Massachusetts  Highway  Association. — At  the  meeting 
of  the  Massachusetts  Highway  Association  on  November 
12,  1907,  Col.  Wm.  D.  Sohier,  of  Boston  and  Beverly, 
made  the  statement  that 

"A  macadam  road,  made  of  crushed  stone  and  bound  with  rolled 
screenings  and  water,  has  gone  out  of  date"; 

and  this  was  not  questioned  by  any  of  the  hundred  or 
more  other  members  present. 

The  situation  cannot  be  better  stated  than  by  quoting 
the  1907  report  of  the  Massachusetts  Highway  Commis- 
sion which  has  built  and  maintains  the  main  parts  of 
one  of  the  finest  road-systems  in  the  United  States;  the 
Commission  being  seconded  in  every  direction  by  the 
members  of  the  Massachusetts  Highway  Association, 
whose  local  roads  join  and  extend  those  of  the  State;  the 
secretary  of  the  Commission,  A.  B.  Fletcher,  being  also 
the  secretary  of  the  Association,  so  that  all  road-builders 
in  the  State  profit  by  each  other's  experience  and  operate 
in  friendly  rivalry;  the  Association  thus  doing  for  Massa- 
chusetts what  the  American  Society  of  Municipal  Im- 

13 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

provements    aims    to    do    for   the    United    States    and 
Canada. 

Massachusetts  Highway  Commission. — The  1907  re- 
port states  as  follows: 

"Perhaps  the  most  important  discovery  of  the  year  is  the  extra- 
ordinarily destructive  effects  upon  stone  roads  of  the  large  number 
of  swiftly  moving  automobiles.  Practically  all  the  main  roads  are 
thus  affected.  It  has  been  noted  that  the  binder  is  swept  from  the 
road,  and  that  the  'number-two  stone'  (J  inch  to  i^  inch  size)  is 
disturbed;  in  some  instances  standing  on  the  surface,  and  in  others 
being  left  in  windrows  along  the  roadside.  The  Commission  is 
satisfied  that  a  material  change  in  the  methods  of  maintaining  stone 
roads  must  be  made.  While  old  methods  have  proved  satisfactory 
in  the  past,  they  fail  under  the  present  usage.  The  automobile  has 
come  to  stay,  and  will  increase  in  numbers,  and  it  must  be  reckoned 
with.  It  must  be  borne  in  mind  that  this  excessive  wear  of  stone 
roads  by  automobiles  is  not  confined  to  Massachusetts.  Reports 
show  that  the  same  trouble  is  experienced  in  all  parts  of  the  United 
States.  The  roads  of  England,  France,  and  other  countries  of 
Europe  are  also  showing  signs  of  destruction  by  the  same  agency." 

The  1908  report  of  the  Commission  says: 

"The  destructive  work  of  automobiles  during  the  past  year  was 
even  more  marked  than  it  was  in  1906." 

Motor-car  Race-track. — The  inability  of  good  macadam 
roadway  to  endure  the  effects  of  many  motor-cars  at  high 
speed  is  shown  in  two  striking  photographs  made  by 
Cortlandt  F.  Bishop  of  Lenox  and  New  York,  whose 
world-wide  road-pictures  are  noted  as  being  unique. 
These  were  made  in  1906  of  a  bend  in  a  French  broken- 
stone  road,  first  shown  in  perfect  form  and  then  again 
two  hours  later  when  the  smooth  macadam  surface  had 
been  torn  up  into  windrows  of  loose  fragments  by  the 
passage  of  an  hundred  racing  motor-cars. 

14 


ROAD   DUST. 


EXPERIMENTAL  WORK. 

These  conditions  and  opinions  have  led  to  a  great 
amount  of  experimental  work,  and  to  the  invention  of 
many  processes  and  devices  having  for  their  object  either 
temporary  treatments  which  should  hold  the  dust  in 
place,  or  better,  the  adoption  of  more  permanent  methods 
which  will  prevent  the  formation  of  dust  and  which  will 
be  applicable  to  the  many  thousands  of  miles  of  existing 
fine  roads  of  broken-stone  which  Europe  has  had  for 
nearly  a  century  and  parts  of  America  for  one-tenth  as 
long,  and  which  must  now  be  saved  from  threatened- 
destruction. 

In  England. — The  English  engineers  have  had  the 
advantage  of  an  abundant  and  cheap  supply  of 
coal-tar,  and  have  taken  the  lead  in  efforts  to  find 
ways  to  get  the  best  results  from  applying  it, — as 
well  as  various  oil-emulsions, — to  parts  of  their 
great  extent  of  fine  and  old  roads.  A  Royal  Com- 
mission was  appointed  in  1906  to  act  upon  the  subject 
of  dust  prevention;  the  authorities  being  moved 
thereto  by  the  wrecking  of  roads  and  the  injuries  to 
adjacent  properties  all  over  Great  Britain.  In  July,. 
1906,  an  English  engineer,  Arthur  Gladwell,  of  Eton,, 
devised  a  method  of  using  bituminous  binder  now 
known  as  the  " Gladwell"  system,  which  will  prob- 
ably be  generally  used  to  make  a  fixed  and  dustless, 
surface  on  macadam  roads,  and  which  is  described 
on  page  111.  Further,  in  May,  1907,  the  English  Road 
Improvement  Association  held,  near  Reading  in  Berk- 
shire County,  competitive  trials  of  the  various  machines 
and  materials  with  instructive  results,  as  noted  at 
page  70. 

IS 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

In  France. — The  French  engineers,  whose  national 
road  system  in  its  general  scheme  and  organization 
and  in  the  details  of  its  execution  and  maintenance,  is 
the  finest  in  the  world,  have  devised  and  widely  used 
methods  for  applying  bituminous  binders  and  coatings 
to  road  surfaces  (pages  65  and  69).  Because  of  the  increas- 
ingly destructive  effects  of  motor-cars  during  1906  and 
1907  upon  great  lengths  of  the  highways  of  France, 
the  Minister  of  Public  Works  organized  an  Inter- 
national Congress  to  meet  at  Paris,  October  11-18, 
1908,  under  the  direction  of  the  Corps  of  Bridges  and 
Roads:  The  " Adaptation  of  Roads  to  Modern  Traffic" 
being  considered  and  discussed  in  all  its  bearings,  and 
the  use  of  coal-tar  and  its  derivatives  both  in  original 
construction  and  as  a  surface  application  being  given 
special  prominence  in  the  program — apparently  because 
this  material  has  so  far  given  the  best  results  on 
French  roads. 

In  the  United  States. — Meantime,  American  engineers 
have  produced  the  best  form  of  bituminous  macadam, 
or  bitulithic,  as  well  as  the  appliances  for  making  it 
of  uniform  reliability  and  upon  a  large  scale,  and 
during  the  past  seven  years  have  built  about  five 
hundred  miles  of  it  in  166  cities  of  the  United  States 
and  Canada  (page  127). 

Americans  have  also  invented  a  method  for  the  con- 
solidation and  asphaltic  treatment  of  sandy  and  other 
soils,  using  a  peculiar  "rolling  tamper"  and  heavy 
asphaltic  oil,  and  have  made  in  California  many 
hundreds  of  miles  of  dustless  roads  which  are  com- 
paratively cheap  and  which  there,  in  the  absence  of 
heavy  rains  and  deep  frosts,  are  durable.  This  con- 
struction was  extended  during  1907  into  Florida  and 

16 


ROAD    DUST. 

Michigan,   in   which   later   the  effect  of  frost  will  be 
shown  (see  page  51). 

CONCLUSIONS. 

From  the  foregoing  summary  it  appears  that  road- 
engineers  who  wish  to  improve  upon  these  various 
methods  which  will  be  detailed,  have  ample  field  in  which 
to  experiment  with  advantage,  while  those  who  want  to 
get  results  at  once,  and  to  check  the  damages  by  motor- 
cars and  the  complaints  by  property  owners,  can  avoid 
methods  which  have  failed  elsewhere,  and  can  use  some 
of  those  which  have  already  been  found  to  be  more  or 
less  successful,  and  which  will  be  described. 


17 


MOISTURE. 


WATER    AS   A   DUST   PREVENTATIVE. 

The  most  common  and  the  most  costly  way  to  prevent 
dust  and  to  preserve  roads  is  to  sprinkle  them  with 
water.  To  keep  roads  always  wet  entails  expense  which 
is  prohibitive  even  for  city  streets  and  park  roadways, 
on  some  of  which  $700  to  $900  per  mile  per  year  is 
expended  for  sprinkling  thirty  to  forty  feet  width,  in 
order  to  make  them  dustless  during  an  average  of  six 
hours  per  day.  During  dry  and  hot  weather  the 
sprinkling  to  be  effective  must  be  repeated  several 
times  per  day  and  the  surface  alternates  between  mud 
and  dust.  When  tried  on  rural  roads  it  has  usually 
been  ineffective,  costly,  and  soon  abandoned. 

Sea-water  is  used  with  results  even  more  unsatisfactory, 
for  although  the  hydroscopic  effect  of  the  deposited  salt 
prolongs  the  duration  of  moisture  on  the  road,  its  presence 
in  the  dust  and  mud  adds  to  their  injurious  effects;  the 
salty,  sticky  mud  damaging  vehicles,  corroding  metals, 
and  loosening  the  fragments  of  stone. 

CALCIUM   CHLORIDE. 

This  in  solution  is  only  to  be  regarded  as  a  substitute 
for  water,  than  which  it  gives  better  effect  at  about  the 
same  cost  or  sometimes  for  less. 

18 


MOISTURE. 

Continuous  moisture  without  frequent  sprinkling 
is  had  by  dissolving  in  water  a  dequilescent  salt  which 
is  deposited  in  the  -road  and  attracts  moisture  from 
the  air.  Calcium  chloride  has,  during  several  years 
past,  been  extensively  used  for  this  purpose  on  roads 
in  England,  where  the  moist  climate  and  humid  air 
offer  favorable  conditions,  and  where  over  two  hun- 
dred of  the  local  road  authorities  are  using  it  increas- 
ingly, its  weak  solution  as  used  being  non-corrosive  and 
harmless. 

Calcium  chloride  (CaCJ)  is  a  white  or  yellowish  white, 
solid,  translucent,  dequilescent,  chemical  salt,  which 
crystallizes  in  large  masses  and  is  a  by-product  of  the 
ammonia  process  of  making  bicarbonate  of  soda  from 
sodium  chloride  (NaCl)  or  common  salt.  It  resembles 
rock-salt  but  is  harder,  and  has  a  sharp,  saline  taste 
which  burns  the  tongue.  It  dissolves  completely  in  water 
in  about  three  hours,  leaving  no  residue,  but  it  evolves 
heat  and  must  be  stirred  to  prevent  caking.  The  cost  in 
England  at  the  Northwich  factory  (20  miles  from  Liver- 
pool) is  30s.  ($7.25)  per  ton,  and  in  the  United  States  at 
Carbondale,  Pa.,  is  $15  per  ton  f.  o.  b.  cars.  It  is  now 
available  in  granulated  form,  dissolving  more  readily. 

METHODS. 

It  is  sometimes  furnished  in  a  forty  per  cent  solu- 
tion which  is  diluted  as  desired,  using  more  or  less  water 
as  the  character  and  condition  of  the  road-material  may 
require.  The  usual  practice  in  England  is  to  apply 
about  three-fourths  pound  of  the  calcium  chloride  per 
square  yard  in  the  first  treatment  of  a  road,  and  at  two- 
month  intervals  afterwards  to  apply  about  one-half  as 

19 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

much,  or  a  total  of  3  pounds  per  square  yard  per  year, 
costing  one  cent  per  square  yard  per  year  for  the  chemical. 
On  much  exposed  roads,  threefold  as  much  chemical  is 
applied  as  often  as  needed  to  keep  the  road  moist. 

The  success  of  this  treatment  in  the  humid  air  of 
England  induced  trials  in  the  United  States,  and  tests 
were  made,  in  September,  1906,  on  the  macadam 
and  gravel  roads  of  Beverly  and  Brookline  in  Massa- 
chusetts near  Boston;  the  results  were  such  that  the 
treatment  was  extended  during  1907  and  continued  in 
1908. 

At  Beverly,  Mass. — The  treatment  of  the  Beverly 
road  is  described  by  Franklin  C.  Pillsbury,  Div.  Engr. 
of  the  Mass.  Highway  Com.,  as  being  applied  in 
September,  1906,  to  a  good  macadam  road,  built  by 
the  State. in  1905,  part  of  it  entirely  shaded  and  part 
open  to  sun  and  wind.  As  a  result  of  the  traffic  of 
fast  motor-cars  passing  almost  continuously  (six  hundred 
and  fifty  being  counted  in  ten  hours  of  one  Sunday), 
the  road  surface  had  lost  its  binder  and  the  fragments 
of  broken  trap  were  exposed  and  beginning  to  ravel. 
The  calcium  chloride  was  bought  in  dry  form  from  the 
Carbondale  Chemical  Co.  of  Carbondale,  Pa.,  at  three- 
fourths  cent  per  pound  f.  o.  b.  cars.  One  application 
consisted  in  dissolving  600  pounds  in  650  gallons  of 
water  by  breaking  the  crystals  into  one  and  one-half 
inch  pieces,  or  less,  stirring  for  three  hours;  filling 
the  tank  of  an  ordinary  watering-cart,  and  sprink- 
ling it  over  1400  feet  in  length  of  eighteen  feet  road; 
passing  two  or  three  times  to  saturate  the  surface.  This 
equalled  one-quarter  pound  of  chemical  per  square  yard. 
As  a  result,  the  dust  and  raveling  ceased;  the  color  was 
darker  because  of  retained  moisture,  but  it  was  difficult 

20 


MOISTURE. 

to  determine  connection  between  this  moisture  and  the 
humidity  of  the  air  as  the  season  was  not  suited  to  obser- 
vation. The  application  as  above  described  was  twice 
repeated  during  1906  and  the  effect  was  good,  especially 
on  a  portion  of  the  road  which  was  made  of  gravel. 
The  treatment  was  continued  during  1907  on  ten  miles 
of  the  same  road,  under  contract  calling  for  the  chemical 
treatment  supplemented  by  sprinkling  with  water.  Two 
applications  of  the  calcium  solution  were  made  in  June, 
1907,  and  one  in  each  of  the  succeeding  months  to  Novem- 
ber 1,  using  one-tenth  pound  of  calcium  chloride  per 
square  yard  each  time.  Water  was  sprinkled  once  on 
each  dry  day  instead  of  four  times  per  day  as  formerly. 
The  contract  cost  was  $331  per  mile  of  surface  averaging 
nineteen  feet  width,  including  watering  as  needed.  The 
complete  treatment  costing  about  the  same  as,  or  slightly 
less  than,  the  former  sprinkling  with  water  only.  Dust 
was  practically  eliminated. 

Improved  Method. — In  the  1907  work  the  crystals 
were  dissolved  at  a  "supply-station"  and  a  saturated 
forty  per  cent  solution  was  used  to  mix  with  the  water 
in  the  sprinkling- tank,  thus  saving  time  and  using  a 
patented  arrangement  by  which  an  ordinary  water-cart 
thus  equipped  covers  three  times  the  area  per  day  which 
was  covered  by  the  first  method.  Six  galvanized  iron 
barrels  of  100  gallons  capacity  each  are  placed  at  hydrants 
about  1000  feet  apart  along  the  road,  and  are  each  filled 
with  40  per  cent  solution,  brought  in  the  watering-cart 
from  the  supply-station.  Each  in  turn  is  then  used, 
with  water  from  the  hydrant,  to  form  600  gallons  of  an 
eight  per  cent  solution  in  the  water-cart  tank,  which  is 
then  applied  to  1000  feet  of  road.  The  contents  of  the 
six  barrels  thus  treat  one  mile  of  nineteen-feet  road  for 

21 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

each  trip  to  the  supply-station  at  a  cost  for  treatment  of 
two  and  one-half  mills  per  square  yard  for  each  treatment. 
The  total  cost  for  the  season  of  the  treatment  and  of  the 
watering,  which  together  made  the  road  dustless  for  five 
months,  was  three  and  one-eighth  cents  per  square  yard 
(or  about  $258  for  one  mile  of  standard  16-feet  road- 
way). 

The  same  roads  were  similarly  treated  in  1908  by 
the  Calcide  Process  Company,  of  402  Sears  Building, 
Boston,  Mass. 

At  Brookline,  Mass. — The  road  treated  at  Brookline 
in  1906  is  a  part  of  Beacon  Street,  having  a  new  telford 
roadway  where  a  four  and  one-half  per  cent  grade 
caused  the  many  motor-cars  to  increase  their  speed  to 
climb  the  hill  with  destructive  effect  on  the  road.  The 
chemical  was  brought  in  a  forty  per  cent  solution  and 
was  diluted  to  eight  per  cent  as  before  described,  and 
was  made  to  so  saturate  the  surface  that  each  particle 
should  be  coated  with  the  chemical  and  thus  kept 
moist,  so  that  when  dragged  up  by  the  suction  of 
the  broad  rubber  tires  of  motor-cars  running  at  high 
speed,  the  damp  particles  should  fall  back  onto  the 
road  to  be  again  bound  to  the  surface  by  the  next 
pressure.  Following  English  practice,  a  much  heavier 
application  was  made  than  that  just  described  at 
Beverly,  with  two  applications  in  two  weeks  and  then 
once  in  three  to  five  weeks,  according  to  the  weather. 
The  road  was  fully  exposed  to  sun  and  wind  and  was 
free  from  dust  when  other  parts  of  the  same  road  needed 
sprinkling.  The  treatment  was  not  continued  in  1907 
on  this  road. 


22 


MOISTURE. 


CONCLUSIONS. 

Tests  have  also  been  made  elsewhere  in  the  United 
States  with  varying  reports  as  to  results.  The  climate 
being  less  humid  than  in  England  doubtless  accounts 
for  less  success.  Its  obvious  advantages  are  that  it  is 
clean,  odorless,  and  easy  to  apply,  and  that  it  is  much 
better  than  water  at  no  greater  cost. 

The  process  is  best  suited  to  special,  limited  cases  of 
fine  residence  streets  adjoining  large  cities  where  a 
municipal  supply  of  hydrant-water  is  available  for  sprink- 
ling, and  it  is  specially  applicable  as  preparation  for 
parades  or  road-races.  At  the  best,  the  effects  of  calcium 
chloride  are  temporary  and  make  no  radical  betterment 
in  the  road  surface.  It  is  not  applicable  to  the  great 
extent  of  existing  broken-stone  roads  which  have  no 
water-supply,  and  which  demand  permanent  treatment 
to  check  wear  in  order  to  reduce  dust. 

SOLUTIONS. 

This  is  more  or  less  true  also  of  other  patented  solutions, 
such  as  "  Akonia"  which  has  been  used  for  several  years 
on  roads  in  Wembley  Park  and  Harrow,  England  (near 
London),  at  a  cost  of  about  $194  per  mile  of  sixteen  feet 
roadway  per  year,  which  also  keeps  the  road  damp  by 
attracting  moisture;  and  "Lymanite"  which  is  a  com- 
bination, by  heating,  of  nitrate  of  soda,  salt,  and  lime, 
to  which  water  is  added  when  cold  and  which  is  then 
sprinkled;  and  "Fitzsimmon's  Patent  dust-layer"  con- 
sisting of  sand  and  soda  fused  and  dissolved  in  water 
for  use. 


23 


OIL  EMULSIONS, 


SUMMARY. 

These  are  more  easily  and  cheaply  applied  than  oils. 
The  use  of  emulsions  avoids  some  of  the  obvious 
objections  to  the  use  of  oils,  which  many  however 
prefer.  The  effects  of  emulsions  on  road-dust  are 
usually  only  temporary,  but  the  results  are  immediate 
and  travel  is  not  interrupted. 

There  are  in  use  many  processes,  patented  and  other- 
wise, for  making  and  applying  emulsions  of  oil,  including 
vegetable  oils,  crude  petroleum,  residual  oil,  creosote-oil, 
oil-tar,  coal-tar,  and  similar  materials,  in  all  of  which 
cases  some  way  is  found  to  emulsify  the  oily  or  bitu- 
minous material  in  water,  so  that  the  mixture  can  be 
spread  by  a  sprinkling  or  a  spraying  device,  or  usually 
by  an  ordinary  watering-cart.  The  results  are  more 
lasting  than  those  from  the  chemical  salts  just  described. 
Most  of  them  can  be  applied  in  any  weather  except 
during  heavy  rain,  and  there  need  be  no  interruption  of 
traffic. 

OBJECTIONS. 

Many  unsuccessful  attempts  have  been  made  to  use 
Pennsylvania  and  Ohio  oils  having  a  paraffin  base,  or 
some  of  the  Russian  oils,  having  a  naphtha  base,  both 

24 


OIL   EMULSIONS. 

in  their  crude  form  and  in  emulsions;  but  these  have 
all  failed,  because  such  petroleums  are  not  suited  to 
roadwork,  refusing  to  bind  the  road  materials,  and 
having  an  ill  odor. 

Oils  having  an  asphaltum  base,  like  some  of  the  petro- 
leums of  California,  Texas,  Indian  Territory,  Kansas, 
and  Kentucky  in  the  United  States,  and  some  from 
Galicia  and  from  Baku  in  Europe,  are  the  only  ones 
suitable;  but  if  any  kind  of  oil  is  sprayed  or  sprinkled  in 
its  crude  form  on  a  hard  macadam  road,  the  result  is 
liable  to  be  most  objectionable  in  regions  of  normal  rain- 
fall, which  may  mix  the  oil  into  injurious  mud.  In  any 
case  the  greatest  care  must  be  taken  to  avoid  getting 
the  oil  onto  objects  along  the  roadside,  and  to  enforce 
rigid  exclusion  from  the  oiled  surface  for  two  or  three 
days,  or  until  all  the  free  oil  has  been  absorbed  or  covered. 
The  difficulties  of  enforcing  such  precautions  have  led 
to  the  use  of  emulsions,  which  soak  into  the  ground 
quickly  and  can  be  used  in  wet  or  dry  weather,  avoiding 
time  of  actual  rainfall. 

All  of  these  oil  mixtures  in  which  acids  or  alkalies  are 
used  to  form  soapy  emulsions  which  will  mix  with  water, 
may  be  expected  to  cause  the  subsequent  road-dust  (even 
though  it  be  slight  in  quantity)  to  be  irritating  and  in- 
jurious to  the  throat,  eyes,  and  skin,  in  proportion  to  the 
acridity  of  the  solvent,  and  some  of  the  mixtures  have 
been  disused  for  that  reason. 

METHODS. 

Boston  Park  Roads. — "Cook's  emulsion"  is  an  old 
form,  recently  again  used  on  the  Boston  park-roadways 
in  September,  1906,  and  consisting  of  100  gallons  of 

25 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

Texas  asphaltic-base  residual  oil,  emulsified  with  twenty- 
five  pounds  of  coarse  soap  in  fifty  gallons  of  hot  water. 
This  was  mixed  with  cold  water  in  such  proportion  that 
the  product  contained  fifteen  per  cent  of  oil  and  was 
applied  from  sprinkling-wagons  to  the  hard  road-surface 
which  had  been  first  covered  with  a  thin,  rolled  layer 
of  fine  screenings  to  absorb  the  oil.  Two  and  three 
distinct  applications  were  made  carefully;  travel  was 
not  interrupted;  the  oil  did  not  pick-up  nor  spatter; 
twelve  miles  of  thirty-feet  roadway  so  treated  cost 
one  and  one-third  cents  per  square  yard,  using  1.04 
pints  of  oil  per  square  yard.  There  was  no  dust 
during,  nor  after,  six  weeks,  and  the  good  effect  con- 
tinued. John  A.  Pettigrew,  Supt.  of  Boston  Parks, 
states  that  the  best  condition  was  obtained  when  the 
one-eighth  inch  layer  of  stone  dust  or  sand  was  only 
so  saturated  with  oil  emulsion  as  to  be  like  moist  brown 
sugar;  more  oil  was  not  desirable. 

Cost. — At  this  rate  the  oiling  of  a  sixteen-feet  road- 
way cost  $127  per  mile,  and  four  applications  per  year 
equaled  $508  per  annum  per  mile. 

The  treatment  was  extended  during  1907  upon  forty- 
four  miles  of  park  roads,  nearly  all  of  which  were  of  hard, 
trap  macadam.  The  soap  used  to  emulsify  the  oil  was 
made  from  cottonseed-oil  and  soda  and  was  bought  solid 
in  barrels  at  four  and  three-fourth  cents  per  pound.  The 
oil  was  residual  Texas  oil  from  which  the  naphtha,  kero- 
sene, and  volatile  parts  had  been  distilled  until  the  resi- 
duum contained  twenty-seven  per  cent  of  asphaltum,  and 
it  was  bought  from  the  Gulf  Refining  Company  as  "  road- 
bed oil"  at  five  cents  per  gallon  in  tank-cars.  The  emul- 
sion was  made  by  mixing  eighteen  pounds  of  soap  with 
fifty  gallons  of  hot  water  and  mixing  this  with  100  gallons 

26 


OIL  EMULSIONS. 

of  the  oil  by  running  them  through  steam-pumps.  The 
stock  thus  made  cost  three  and  nine-tenth  cents  per  gallon 
and  was  supplied  to  the  ordinary  sprinkling- wagons,  in 
which  water  from  the  hydrants  made  the  required  solu- 
tions of  sixteen  per  cent  of  oil  for  the  first  application, 
or  of  eight  per  cent  or  five  per  cent  as  required  for  the 
subsequent  applications,  which  followed  at  intervals  of 
ten  days  to  twenty  days,  using  a  total  of  one  and  one- 
half  pints  of  oil  per  square  yard  from  April  15  to 
November  1,  or  six  and  one-half  months,  at  a  cost 
of  two  cents  per  square  yard,  or  $187  per  mile  of 
sixteen-foot  roadway;  this  included  all  except  the  cost 
of  sanding  twice  during  the  season ;  meantime  the  asphal- 
tum  in  the  oil  bettered  the  surface  and  less  repairs  were 
needed.  The  results  of  this  oil-emulsion  treatment  were 
satisfactory  and  the  dust  was  perfectly  laid.  The  former 
cost  of  watering  the  same  roads  during  a  similar  period 
had  been  three  and  one- third  cents  per  square  yard. 

Conclusions. — Mr.  Pettigrew  considers  that  the  use 
of  the  residual  oil  itself  would  be  better  than  of  the 
emulsion  above  described,  but  the  emulsion  permits 
that  carriages  may  follow  immediately  after  the  sprink- 
lers, whereas  oil  application  would  necessitate  closing 
the  roads  for  several  days. 

Chicago  Park  Roads. — Experimental  work  was  done 
on  the  park  roadways  of  Chicago  during  the  spring  and 
summer  of  1907,  having  the  primary  purpose  of  laying 
the  dust,  using  crude  and  residual  asphaltic  oils — alone, 
mixed,  and  in  soap-emulsions  of  varied  proportions. 
The  object  was  to  find  a  material  which  would  not 
be  sticky  but  would  form  a  bond  both  below  and 
above  the  surface  and  would  permit  travel  to  be  un- 
interrupted and  without  injury.  The  roads  were  maca- 

27 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

dam,  part  limestone  and  part  granite;  some  bound 
with  limestone  screenings  and  some  with  gravel.  The 
best  results  seem  to  have  been  had  with  a  hot  emulsion 
of  Kansas  fuel-oil  (being  a  residual  oil  costing  three 
and  one-half  cents  per  gallon  from  which  the  naphtha 
and  volatile  parts  had  been  distilled),  California  as- 
phaltum,  ninety-eight  per  cent  pure,  costing  ten  cents 
per  gallon,  and  soft  naphtha  soap  of  the  "tak-a-nap" 
brand,  which  latter  mixed  best  with  the  hard  lime-water 
of  Lake  Michigan. 

Mixture. — The  emulsion  was  made  by  boiling  sixty 
gallons  of  water  with  live  steam  and  adding  fifteen 
pounds  of  soap  and  boiling  five  minutes;  adding  sixty 
gallons  of  the  Kansas  residual  oil  and  pumping  them 
from  one  vat  to  another  for  five  minutes  to  mix;  then 
adding  twenty-five  gallons  (half  a  barrel)  of  California 
asphaltum,  ninety-eight  per  cent  pure,  and  pumping 
the  whole  for  twenty  minutes  to  emulsify  the  mixture, 
which  cost  six  and  one-quarter  cents  per  gallon.  This 
was  then  sprinkled  upon  the  thoroughly  cleaned  and 
swept  surface  of  the  hard  macadam  roads  at  the  rate 
of  one-fifth  gallon  per  square  yard  for  each  coating, 
and  five  of  these  coats  were  applied  in  as  rapid  suc- 
cession as  possible.  Meantime  any  small  holes  in  the 
surface  were  filled  with  sweepings  from  the  roadside 
to  be  cemented  with  the  next  hot  emulsion  application. 
Roads  treated  in  this  way  in  Lincoln  Park  on  June  19, 
1907,  remained  dustless  and  in  good  order  until  the 
middle  of  October,  or  for  four  months,  with  no  other 
treatment.  Traffic  continued  during  and  after  the 
applications  with  no  bad  results,  and  there  was  no 
bad  odor. 

Cost. — The  cost  of  this  work  was  excessive,  being  at 

28 


OIL  EMULSIONS. 

the  rate  of  $586  per  mile  of  sixteen-feet  road  for  the 
emulsion  alone,  to  which  was  to  be  added  the  cost  of 
application  and  of  patching. 

WESTRUMITE. 

"Westrumite"  is  a  patented  emulsion  of  petroleum 
and  ammonia,  forming  a  sort  of  soap  which  is  soluble 
in  water.  It  was  invented  in  Germany,  extensively  used 
there  and  in  England  (especially  on  stretches  of  road 
to  be  used  for  parades  or  for  motor-car  races),  and  was 
first  brought  to  the  United  States  in  1905,  when  it  was 
used  experimentally  on  Staten  Island,  N.  Y.,  and  on 
the  Midway  Plaisance  in  Chicago. 

It  is  designed  to  suppress  dust  on  any  kind  of  road, 
preventing  soakage  of  water  and  acting  somewhat  as  a 
binder.  It  has  a  disagreeable  odor  for  two  days  after 
application,  and  makes  a  macadam  roadway  somewhat 
slippery. 

At  Chicago. — On  the  Midway  Plaisance  the  traffic  was 
restricted  to  carriages,  motor-cars,  and  bicycles.  The 
roadway  was  of  limestone  macadam  bound  with  lime- 
stone screenings,  and  was  very  clean  when  it  was  first 
sprinkled  with  westrumite  on  August  21  and  22,  1906. 
A  ten  per  cent  solution  (one  part  westrumite  to  nine 
parts  water)  was  applied  from  ordinary  watering-carts, 
0.31  and  0.175  gallon  of  the  solution  per  square  yard 
being  used  for  one  application.  At  successive  intervals 
of  about  eight  days  the  application  was  repeated,  using 
0.17  gallon  (or  one-sixth  gallon)  of  a  five  per  cent  solu- 
tion per  square  yard,  the  cart  passing  twice  to  make 
each  "application,"  of  which  ten  in  all  were  made 
during  eighty-three  days,  during  which  time,  night  and 

29 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

day,  there  was  no  dust.  The  added  cost  to  that  of 
using  plain,  free  water  was  two  and  two-tenths  mills 
per  square  yard  per  month,  or  forty-five  per  cent  more 
than  for  free  water  only.  This  cost  is  based  upon  a 
rate  of  seven  and  one-half-cents  per  gallon,  or  $20 
per  ton,  for  the  westrumite,  and  equals  $21  per  month 
per  mile  of  a  sixteen-feet  roadway.  Park  superintendent 
J.  F.  Foster  considers  that  if  the  traffic  had  been  un- 
restricted and  heavy,  the  applications  needed  to  give 
the  same  results  would  have  been  double  the  above- 
named  amounts  applied  at  four-day  intervals,  equaling 
fourfold  the  above  cost. 

In  Europe. — In  France,  "westrumite,"  or  some  one  of 
several  similar  compounds  (one  known  as  "coudrogenit") 
is  much  used  to  control  dust  for  special  occasions  of 
short  duration,  and  various  devices  other  than  the  com- 
mon watering-cart  are  used.  On  parkways  and  suburban 
roads  where  water-mains  are  at  the  roadside,  water  under 
pressure  is  sometimes  lead  through  a  hose  to  a  special 
nozzle  into  which  oil,  or  westrumite  or  other  emulsion, 
is  fed  by  a  branch  pipe  from  a  reservoir  which  is  some- 
times carried  like  a  knapsack  on  the  back  of  the  man 
holding  the  nozzle,  or  from  a  barrel  drawn  on  a  hand- 
cart by  another  man.  The  special  nozzle  consists  of  two 
conical  pieces  fitting  together  so  that  the  water  stream 
acts  by  aspiration  to  draw  the  oil  or  emulsion,  which 
then  mixes  with  the  water  in  the  nozzle  and  is  spread 
upon  the  roadway. 

In  Germany  trials  of  westrumite  on  roads  in  and 
near  Dresden  (as  reported  in  the  Minutes  of  the  Inst.  of 
Civil  Engineers  of  Great  Britain  for  December,  1907), 
gave  results  which  were  in  every  way  satisfactory  as  to 
prevention  of  dust;  but  the  cost  was  four  to  six  times 

30 


OIL    EMULSIONS. 

as  great  as  that  of  ordinary  watering,  so  that  there  was  no 
general  use  because  of  the  prohibitive  expense. 

In  the  United  States. — The  excessive  costs  for  the 
transient  results  seem  likely  to  limit  the  use  of  "west- 
rumite" in  the  United  States  to  special  cases  and  to 
emergencies,  especially  as  more  permanent  or  more 
effective  methods  are  coming  into  use. 

In  1907,  westrumite  was  used  in  a  different  way  at 
St.  Paul,  Minn.,  to  saturate  the  layers  of  a  granite 
macadam  road  during  its  construction.  A  ten  per  cent 
solution  of  westrumite  was  sprinkled  on  the  crushed 
stone  before  and  during  rolling,  and  a  fifty  per  cent 
solution  on  the  limestone  screenings  binder,  and  a  fifteen 
per  cent  solution  on  the  surface  of  the  finished  road, 
aggregating  about  one  gallon  per  square  yard.  This 
treatment  must  have  added  twelve  cents  per  square  yard 
to  the  cost  of  the  completed  road,  which  is  said  to  be  kept 
free  from  dust  by  sprinkling  with  water  once  in  ten  days. 

PATENTED   EMULSIONS. 

"Westrumite  2"  is  a  similar  ammonia  emulsion  of 
natural  bitumen,  used  in  a  somewhat  similar  way  for  the 
same  purposes. 

"Pine-oiline"  was  a  preparation  similar  to  westrumite, 
but  its  manufacture  has  been  joined  with  that  of  the 
latter. 

"Apulvite"  is  a  similar  product  which  was  used  in 
Geneva,  Switzerland,  as  was  westrumite;  but  each  failed 
there  to  give  the  expected  results  as  they  did  not  resist 
rainfall. 

Another  patented  soapy  mixture  is  "Sandisize"  formed 
by  mixing  potash  with  the  by-product  of  wool-washing 

31 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

wastes  left  after  extracting  the  major  part  of  the  grease. 
It  is  said  that  the  resulting  emulsion  does  not  clog  the 
sprayer  and  that  it  has  marked  hygroscopic  properties. 
It  was  originated  and  first  used  in  Scotland  in  1905, 
where  it  was  patented,  and  it  is  also  patented  in  the 
United  States.  The  treatment  in  Scotland  of  one  mile  of 
sixteen-foot  roadway  with  ten  per  cent  solution  costs  for 
one  application  $21.50;  three  or  four  applications  per 
season  preventing  dust. 

"Crempoid  D"  is  a  mixture  of  glue  and  bichromate  of 
potash,  with  oil  added  to  soften  it,  and  it  also  is  applied 
from  a  spraying-machine,  or  in  a  weak  solution  from  a 
watering-cart,  and  has  been  tried  at  Islington  near 
London,  and  at  Bladshall  in  Midlothian.  It  was  entered 
in  competitive  tests  before  the  English  Roads  Improve- 
ment Association  in  May,  1907,  and  was  reported  to  have 
practically  disappeared  from  the  road  in  a  fortnight. 

Other  crude  oil  emulsions  or  mixtures  are  the  English 
"Dustabato  System,"  "Newstrand,"  and  "Riley's  Com- 
pound" 

"Dustoline"  an  American  preparation  made  in  Sum- 
mit, New  Jersey,  is  a  thin,  clear,  yellow  oil  having  no 
"body"  which  can  furnish  any  mechanical  bond  of  the 
road-material.  It  was  used  in  1907  on  about  five  miles 
of  macadam  roads  at  Newport,  R.  I.,  in  two  applications, 
two  weeks  apart,  without  removing  the  layer  of  dust, 
using  from  one-fourth  to  one-fifth  gallon  per  square  yard 
for  both,  at  a  total  cost  for  material  and  labor  of  three 
and  one-half  cents  per  square  yard.  It  costs  seven  and 
one-half  cents  per  gallon  in  car  and  is  said  to  be  effective 
in  laying  dust,  and  to  be  perfectly  satisfactory  to  the 
local  officials,  but  to  have  had  injurious  effects  on  rub- 
ber tires  and  on  clothing. 

32 


OIL    EMULSIONS. 

"  Terracolia"  is  an  ammonia  emulsion  of  oil  (with  ten 
per  cent  of  coal-tar),  and  is  a  thick,  brown,  molasses-like 
mixture.  It  was  used  during  1907,  in  five  per  cent  and 
twenty  per  cent  solutions,  in  Montclair,  New  Jersey,  and 
in  Prospect  Park,  Brooklyn,  and  in  Bronxville,  New  York, 
and  near  Boston,  and  is  said  to  have  given  good  results  in 
laying  the  dust,  but  at  high  cost. 

" Pulvicide"  is  an  English  compound  composed  of 
coal-tar  creosote  50  gallons,  coal-tar  pitch  112  pounds, 
resin  252  pounds,  which  are  mixed  and  heated  until 
solution  forms.  Twenty-eight  pounds  of  caustic  soda 
is  then  dissolved  in  eighteen  gallons  of  water  and  poured 
into  the  former  mixture,  stirring  until  combined.  The 
resulting  emulsion  is  mixed  with  water,  usually  in  the 
ratio  of  thirty  gallons  to  300  gallons  of  water,  and  this 
is  sprinkled  over  the  road-surface  from  an  ordinary 
watering-cart,  with  the  result  of  depositing  the  contained 
bituminous  material  on  the  surface,  where  it  has  proved 
effective  in  laying  the  dust  for  periods  of  ten  days,  after 
which  another  application  is  made.  During  1906  it 
was  used  by  forty  or  more  road  authorities  in  England  at 
costs  not  stated.  It  was  entered  in  competitive  tests 
before  the  English  -  Roads  Improvement  Association  in 
May,  1907,  and  was  reported  to  have  practically  dis- 
appeared in  a  fortnight. 

"Ermenite"  is  an  emulsion  of  cottonseed-oil,  coal-tar, 
and  soap.  It  is  formed  by  treating  hot  cottonseed-oil 
with  sulphuric  acid,  and  then  washing  and  mixing  it 
with  four  times  its  weight  of  crude  tar.  This  mixture  is 
then  emulsified  with  hot  caustic  soda  and  is  then  diluted 
with  water  until  it  contains  twenty  per  cent  of  tar.  This 
twenty  per  cent  solution  is  mixed  in  the  tank  of  an  ordi- 
nary watering-cart  with  four  volumes  of  cold  water 

33 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

and  is  sprinkled  on  the  road  without  mechanical  stirring. 
It  was  used  during  1906  at  Holmes  Chapel  in  Cheshire, 
England,  at  a  cost  not  stated.  When  applied  in  the 
competitive  test  as  described,  it  disappeared  from  the 
road  in  a  week. 

"Hahnite"  is  an  emulsion  formed  by  mixing  oil  and 
carbolic  acid  heated  to  150°  F.,  with  asphalt  and  tar, 
without  saponifying  the  oil.  This  is  mixed  with  water 
in  an  ordinary  watering-cart  equipped  with  a  mechanical 
stirrer  actuated  from  the  wheel-axle,  and  is  sprayed  upon 
the  road  where  it  oxidizes,  with  the  effect  of  laying  the 
dust.  It  has  been  used  in  England  in  Surrey,  at  Rich- 
mond on  the  Petersham  road,  and  by  the  Kingston 
Corporation  on  the  Riverside  road,  all  suburbs  of  London. 
In  the  competitive  test  above  described,  it  had  practically 
disappeared  from  the  road  in  a  month. 

"Rapidite"  is  a  French  compound  of  powdered  asphalt 
mixed  with  water,  probably  containing  an  acid  or  an 
alkali  as  an  emulsifier. 


CONCLUSIONS. 

None  of  these  emulsions  claim  to  be  of  more  than 
temporary  effect,  and  in  regions  like  the  south  of  France 
and  in  the  French  and  Italian  Riviera,  the  winter 
playground  of  Europe,  the  good  temporary  effects 
on  the  roads  have  in  some  cases  been  offset  by  the 
injurious  effects  to  the  road-users,  as  stated  on  page  25. 
In  regions  of  heavy  or  frequent  rainfall,  the  necessity 
for  renewal  after  rains  has  added  to  the  cost  of  their  use. 
They  do  not  seem  to  be  generally  adapted  to  American 
conditions. 

34 


OIL   EMULSIONS. 


MECHANICAL   EMULSIFIER. 

Good  results  were  expected  from  an  English  machine 
known  as  the  "Emulsifix"  by  which  tar-oil  or  other 
road-oil  is  mechanically  emulsified  in  water  without 
the  objectionable  aid  of  acid,  alkali,  or  heat;  the 
mixture  being  sprayed  upon  the  road  before  it  could 
separate.  This  machine,  having  been  elsewhere  used, 
was  entered  with  seven  others  at  the  competitive  trials 
and  tests  before  mentioned  which  were  held  by  the 
English  Road  Improvement  Association  near  Reading 
in  Berkshire  County  on  May  24-27,  1907.  It  then 
failed  to  give  satisfactory  results,  but  some  later  modi- 
fication in  machine  or  material  may  supply  the  lack 
then  shown. 

Method  of  Operation. — It  consists  of  a  horse-drawn 
wagon  carrying  a  large  tank  divided  into  two  compart- 
ments, one  for  water  and  the  other  for  oil-tar  or  oil;  a 
smaller  and  separate  tank  is  in  the  rear,  in  which  the 
oil  and  water  meet  and  are  there  mixed  by  rapidly 
revolving  blades  actuated  from  the  wheel-axle,  forming 
a  mechanical  emulsion  which  is  forced  through  a  pipe  in 
a  finely  subdivided  state  onto  and  into  the  road-surface. 
No  heat  is  used,  and  valves  regulate  the  proportions 
mixed  and  the  quantities  used.  Tar-oil  carrying  forty 
per  cent  of  tar  is  preferred  for  use  in  the  "Emulsifix," 
and  the  treatment  consists  in  applying  two  coats  of  five 
per  cent  emulsion  on  two  consecutive  days,  and  afterward 
at  intervals  of  a  fortnight  or  three  weeks  as  required. 

Results. — There  is  no  need  to  close  the  road  while  the 
treatment  is  in  progress,  and  one  wagon  is  said  to  suffice 
to  keep  fifty  or  sixty  miles  of  road  in  good  condition 

35 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

with  eight  treatments  per  annum,  at  a  yearly  cost  of  $35 
to  $50  per  mile  of  twenty-four-feet  road. 

The  machine  is  said  to  have  given  good  results  at 
Knutsford,  Whitington,  and  Chilford,  all  near  Man- 
chester; but  the  adverse  report  of  the  Road  Improve- 
ment Association  judges  will  cause  these  claims  to  be 
questioned.  Such  results  as  are  claimed  would  be  very 
desirable  and  the  device  seems  to  have  capabilities 
worthy  of  improvement,  as  its  success  would  enable  the 
use,  at  low  cost,  of  oil  emulsions  free  from  acids. 


36 


OILS. 


SUMMARY. 

Attempts  have  been  made  since  1894  to  use  crude 
petroleum  or  some  of  its  derivatives,  or  some  oily  by- 
product of  gas  manufacture,  to  control  and  prevent 
dust.  These  attempts,  many  of  them  unsuccessful, 
have  led  to  knowledge  as  to  the  kinds  of  oil  which 
are  unsuitable  and  as  to  the  conditions  which  cause 
failure  (page  25).  Experience  has  also  shown  that  oils 
of  certain  characteristics,  properly  applied  under  the 
right  conditions,  give  good  results  at  reasonable  costs. 
There  will  undoubtedly  be  a  great  increase  in  the  near 
future  in  the  use  of  heated  asphaltic  oils,  not  only  to 
prevent  dust  but  also  to  improve  sandy  roads  and  to 
preserve  gravel  and  broken-stone  roads,  though  there 
are  as  yet  but  few  examples  of  the  latter  (see  page  42). 

PETROLEUM. 

Crude  petroleums,  which  contain  the  largest  proportion 
of  pure  asphaltum,  give  the  best  results.  Petroleum, 
without  asphaltum,  having  a  paraffin  base,  like  the 
Pennsylvania  and  Ohio  oils,  and  those  having  a  naphtha 
base,  like  some  of  the  Russian  oils,  are  useless,  refusing 
to  bind  and  having  ill  odors  and  making  greasy  slime. 
Some  of  the  California  oils  as  they  come  from  the  wells 

37 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

contain  so  much  asphaltum  that  they  are  valuable  mainly 
for  it;  some  of  the  wells  in  the  Bakersfield  district  (100 
miles  N.N.W.  of  Los  Angeles),  especially  the  "Adeline" 
wells,  produce  petroleums  having  sixty  to  eighty-four  per 
cent  of  pure  asphaltum.  Such  crude  oils  are  there  used 
on  roads  with  good  results  not  otherwise  equaled,  by 
following  methods  described  on  page  51. 

Residuum. — Petroleums  with  asphaltic  bases  from  the 
Beaumont  fields  of  Texas  and  from  Kentucky,  Kansas, 
and  Indian  Territory,  and  some  of  the  Russian  oils  from 
Baku,  and  those  from  Galicia  in  Austria,  and  from 
Borneo  in  the  the  far  East,  which  are  mainly  valuable 
for  their  volatile  parts,  leave  residuum  which  is  effective 
for  road  work  after  distillation  has  removed  the  naphtha, 
gasolene,  illuminating-oil,  and  other  elements  which 
would  be  detrimental  for  roadwork.  The  by-products 
thus  left  are  variously  known  as  "  residual  oil,"  "  roadbed- 
oil,"  "fuel-oil,"  "steamer-oil,"  and  other  trade  names. 

Test. — These  are  usually  thick,  black  or  brown  viscid 
substances,  whose  proportion  of  asphaltum  can  easily  be 
determined  by  evaporating  a  weighed  sample  in  an  open, 
metal  pan  over  gentle  heat  until  the  residuum  has  the 
hardness  of  commercial  "D"  asphalt  at  the  standard 
temperature  of  60°  F.  The  weight  of  this  residue  com- 
pared with  the  original  weight  of  the  sample  before 
evaporation  should  show  twenty-five  to  twenty-eight 
per  cent,  or  better,  forty  per  cent.  With  less  than 
twenty-five  per  cent  it  is  not  well  suited  to  roadwork. 
Some  samples  so  tested  will  show  no  asphaltum  what- 
ever, although  there  may  have  been  reason  to  expect 
to  find  it.  Test  should  also  be  made  for  the  amount 
of  contained  water,  which  should  not  exceed  two  per 
cent. 

38 


OILS. 

Slow  distillation. — It  is  observed  that  the  residuum 
from  oil  which  is  light  in  asphalt  is  better  suited  for  road- 
work  when  the  distillation  is  done  slowly,  and  at  lower 
temperature  than  generally  used  by  the  refiners  when  the 
production  of  gasolene  and  illuminating-oil  is  the  main 
object,  and  when  the  ill  effects  of  high  heat  on  the  asphal- 
tum  are  not  considered.  When  the  distillation  is  done 
at  300°  F.  instead  of  at  600°  to  700°  F.,  two  days  are 
required  instead  of  one  day  to  do  the  refining;  but  the 
resulting  asphaltic  residual  oil  is  much  better  for  road- 
work,  and  more  nearly  resembles  the  naturally  heavily 
asphaltic  oils  of  California,  the  contained  asphaltum 
showing  much  more  of  the  great  ductility  of  the  Cali- 
fornia asphaltum,  which  largely  accounts  for  its  success 
in  road  and  pavement  work. 

CALIFORNIA    PETROLEUM    SHIPMENT. 

California  crude  petroleum,  heavy  in  asphaltum  which 
is  ninety-eight  per  cent  pure,  may  at  some  future  time 
be  available  for  that  general  use  which  is  now  prevented 
by  difficulties  of  transportation.  Railroad  rates  across 
the  continent  are  prohibitative,  and  the  ordinary  eight- 
inch  pipe  line  which  crosses  at  Panama  and  supplies  fuel- 
oil  to  the  canal  works  has  not  yet  been  used  to  pass  this 
heavy,  thick  oil  for  road  work,  it  having  been  found 
in  California  that  delivery  through  such  a  line  is  too 
slow  to  be  practicable  even  under  the  most  favorable 
circumstances.  This  led  the  Southern  Pacific  Railroad 
to  begin  building,  in  1907,  a  282-mile  specially  designed 
pipe  line  for  delivering  this  heavy  oil  at  Porta  Costa  on 
an  arm  of  San  Francisco  Bay.  This  line  is  an  eight-inch 
steel  pipe  rifled  with  six  grooves  making  a  complete  turn 

39 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

every  ten  feet,  giving  a  rotary  motion  to  the  stream. 
Ten  per  cent  of  water  introduced  with  the  oil  is  found 
to  be  thrown  by  centrifugal  force  to  the  outside  of  the 
stream  of  oil,  where  it  acts  as  a  lubricant  between  the  oil 
and  the  pipe,  reducing  friction  and  facilitating  the  pas- 
sage of  the  oil  without  the  need  for  heating  it,  as  has 
formerly  been  tried.  The  pipe  line  is  expected  to  be 
in  operation  in  1908,  so  that  tank-ships  may  be  able  to 
deliver  the  oil  at  reasonable  cost  at  Atlantic  ports. 

Substitutes. — Until  such  time  there  is  no  reason  why 
the  best  Kentucky,  Texas,  or  other  asphaltic  petroleums, 
when  refined  by  the  slow  process  as  above,  should  not 
produce  an  asphaltic  residual  oil  which  will  give  good 
results  when  properly  used  (see  page  52). 


FAILURES. 

It  has  been  a  common  thing  during  the  past  few 
years  for  some  county  official,  to  whom  all  oils  look 
alike,  to  buy  a  car-load  of  oil  of  unknown  quality 
and  to  have  it  sprinkled  from  watering-carts  in  unre- 
stricted quantity,  without  experienced  direction  or  regard 
to  details  of  road  condition  or  of  weather,  and  without 
attempt  to  remove  or  to  cover  the  greasy  mud  caused  by 
sudden  rainfall,  or  to  warn  the  traffic  to  avoid  the  fresh 
oil.  The  results  have  often  been  most  objectionable  to 
residents  and  to  road-users,  and  have  caused  opposition 
and  waste  which  good  management  would  have  avoided. 
One  writer  says: 

"  The  ordinary  road  sprinkled  with  petroleum  is  probably  the  most 
obnoxious  possible.  The  oil  is  everywhere — on  plants,  bushes, 
trees,  vehicles,  and  clothes." 

40 


OILS. 

Such  criticisms  are  based  on  reason,  but  the  objectionable 
features  are  avoidable.  There  have  been  failures  from 
applying  oil  during  cool  weather  or  upon  roads  not 
thoroughly  dry,  and  from  the  effect  of  rain  soon  after 
application.  Rain  tends  to  form  an  emulsion  with  the 
free  oil  and  makes  a  sticky,  injurious  mud,  and  leaves 
the  road-surface  soft  (see  page  15). 

HISTORY. 

Crude  petroleum  was  probably  first  used  for  road  work 
at  Santa  Barbara,  California,  in  1894,  and  its  use  in  that 
State  has  since  been  general  and  in  most  cases  successful. 
The  success  has  been  primarily  due  to  the  peculiar 
character  of  some  of  the  local  petroleums  of  which,  as 
stated  on  page  38,  there  are  those  containing  forty  to 
eighty-four  per  cent  of  pure  asphaltum,  coming  from  the 
wells  as  a  thick,  viscid,  black  liquid,  which  looks  like 
molasses  and  must  be  heated  to  give  it  the  fluidity  neces- 
sary for  use;  some  contain  no  asphaltum  and  are  useless 
for  road  work.  The  good  results  from  oiling  California 
roads  are  due  secondarily  to  the  semi-arid  climate,  char- 
acterized by  dry,  hot  periods  without  rain,  and  to  the 
methods  and  appliances  locally  evolved  for  forming 
durable,  dustless  roads  of  oiled  and  tamped  sand  or 
earth,  as  described  on  pages  51,  55. 

PRESERVATION  OF  PRESENT  ROADS. 

The  present  interest,  however,  attaches  mainly  to  the 
treatment  of  the  surface  of  existing  standard,  macadam 
and  telford  roads,  formed  of  hard,  crushed  rock,  located 
in  the  central,  southern,  and  eastern  States,  and  in 

41 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

Europe,  where  the  peculiar  California  oil  is  not  yet  sold, 
and  where  asphaltic  residual  oils  like  some  of  those  from 
Texas,  Kansas,  Kentucky,  and  Indian  Territory  for 
the  United  States,  and  from  Galicia  in  Austria,  and 
Baku  in  Russia  for  Europe,  are  the  only  ones  available. 

OIL    ON    STONE   ROADS. 

There  are  but  few  instances  of  such  successful  use, 
some  of  which  are  described  in  order  of  date. 

IN   RHODE    ISLAND. 

The  town  of  Cranston,  Rhode  Island,  has  thirty 
miles  of  macadam  roads  formed  of  the  native  blue 
granite,  which  is  not  quite  so  hard  as  trap,  of  which 
granite  the  roads  of  Cranston  have  been  built  and 
maintained  since  1890  by  P.  J.  Conley,  highway  sur- 
veyor. As  the  town  adjoins  the  City  of  Providence, 
some  of  these  roads  are  trunk  lines  subject  to  heavy 
commercial  traffic,  and  they  are  also  subject  to  the 
motor-car  travel  incident  to  such  location.  Since  1900 
Mr.  Conley,  induced  thereto  by  accounts  of  success 
from  oil  treatment  in  California,  has  each  year  sprinkled 
these  roads  with  residual  Kansas  asphaltic  oil  (with 
probably  twenty-five  per  cent  asphalt)  bought  from  the 
fuel-oil  department  of  the  Standard  Oil  Company  at 
Bayonne,  New  Jeresy,  for  four  and  six-tenths  cents  per 
gallon,  f.o.b.  cars  at  Cranston. 

Cost. — This  has  been  applied  cold  from  an  ordinary 
sprinkling-cart,  when  the  roads  were  perfectly  dry,  using 
about  one-seventh  gallon  per  square  yard,  or  1200  gal- 
lons per  mile  of  road,  at  a  cost  of  $60  per  mile  for 
each  application. 

42 


OILS. 

Results. — Two  such  applications  have  usually  been 
made  each  year.  One  sufficed  in  1907.  Dust  has 
been  controlled.  Some  damage  was  done  to  motor-cars, 
carriages,  and  clothes  during  the  three  or  four  days 
following  an  application,  and  during  and  immediately 
after  hard  rains,  by  the  picking-up  of  coagulated,  oily 
dust;  but  that  the  results  on  the  whole  have  been 
satisfactory  is  shown  by  the  continuance  of  the  treat- 
ment from  year  to  year  for  eight  consecutive  years. 
The  cost  has  averaged  $120  per  mile  per  year,  or 
one-sixth  the  former  cost  of  watering.  It  has  without 
doubt  increased  the  life  of  the  road,  but  the  tenacity 
of  the  asphalt  in  the  oil  is  not  sufficient  to  prevent 
ravelling  under  unfavorable  conditions. 

IN  ENGLAND. 

At  Liverpool,  England,  in  1902,  and  during  two 
years  following,  experiments  were  made  on  fine  mac- 
adam roads  by  applying  various  oils  and  mixtures, 
hot  and  cold;  among  others  was  crude  Texas  pet- 
roleum. The  importance  of  the  contained  asphalt 
was  not  then  appreciated  and  no  record  was  kept  of 
this  feature.  Applications  were  made  during  dry 
weather  only,  using  in  1902  an  ordinary  hand-water- 
ing can  and  spreading  one-eighth  gallon  per  square 
yard.  Of  the  six  materials  tried,  petroleum  was  the 
least  satisfactory.  In  1903  it  was  again  applied, 
through  hand-syringes  with  fine  roses,  using  one-eighth 
gallon  per  square  yard,  costing  one-fourth  cent,  at  in- 
tervals of  three  weeks.  The  conclusion  was  that 
"creosote-oil"  was  better,  as  described  on  page  62. 


43 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


IN   AUSTRALIA. 

In  1903,  at  Sidney,  N.  S.  W.,  Australia,  macadam 
roads  of  very  hard  blues  tone  were  oiled,  and  the  de- 
tails are  given  by  John  Colin  Rose,  Assoc.  M.  Inst. 
C.  E.,  borough  engineer  of  North  Sidney.  The  oil 
was  residual,  from  an  asphalitc  American  petroleum 
left  after  the  extraction  of  the  volatile  parts,  and  con- 
sisted of  part  of  the  petroleum  with  vaseline  and 
bitumen.  One-fourth  gallon  per  square  yard  was 
applied  cold  from  hand-watering  cans  with  small  per- 
forations, as  this  method  was  found  to  best  avoid 
excessive  and  unequal  distribution  and  to  be  the 
cheapest  and  most  effective  way.  It  was,  however, 
found  necessary  to  shield  the  rails  of  the  electric  street 
railway  during  the  operation  of  oiling.  The  work 
began  in  November  (the  commencement  of  the  Aus- 
tralian summer),  and  was  confined  to  dry  days,  as  it 
was  found  that,  if  a  heavy  shower  immediately  followed 
the  oiling,  the  operation  was  wasted  and  that  the  oil 
was  washed  into  the  gutters. 

Cost  and  Results. — With  labor  at  twenty  cents  per 
hour  and  oil  at  six  cents  per  gallon,  the  cost  per 
square  yard  was  one-fourth  cent  for  labor  and  one 
and  three-eights  cents  for  oil,  or  one  and  six- tenths  cents 
total.  The  results  were  that  the  cementing  cushion 
formed  by  the  bitumen  caused  the  fragments  of  stone  to 
cohere,  thus  reducing  the  noise  of  traffic,  banishing  mud 
and  dust,  increasing  the  life  of  the  road,  and  reducing 
the  cost  of  maintenance.  These  results  lasted  after  each 
treatment  for  a  minimum  of  two  months  to  a  maximum 
of  four  months.  In  1906  one  of  the  roads  which  had 

44 


OILS. 


been  thus  treated  for  two  and  one-half  years  remained 
in  first-class  condition,  with  the  binding  material  plastic 
and  much  like  india-rubber. 


IN   TENNESEE. 

At  Jackson,  Tennessee,  in  1905,  the  U.  S.  Office  of 
Public  Roads,  Logan  Waller  Page,  Director,  did  some 
instructive  work  and  used  a  number  of  materials  upon 
macadam  roads;  among  them  were  crude  and  residual 
Texas  and  Louisiana  oils. 

Light  Crude  Oil. — The  light,  crude  oil  was  applied 
to  the  cleanly-swept  surface  of  the  macadam,  into  which 
forty-eight  one  hundredths  gallon  per  square  yard  soaked 
very  quickly  and  left  no  asphaltic  coating  on  the  surface. 
It  was  first  applied  from  a  hose  attached  to  a  tank- 
wagon,  followed  by  nine  men  with  brooms  to  spread 
it  by  sweeping;  this  cost  fifty-seven  one  hundredths 
cent  per  square  yard  for  the  labor  only.  A  street- 
sprinkler  operated  by  one  man,  then  spread  600  gal- 
lons of  oil  over  1200  square  yards  of  road  in  fifteen 
minutes,  or  more  than  twice  as  rapidly  as  the  tank- 
wagon  and  nine  men.  This  light,  crude  oil  produced 
slight  effect,  and  it  was  decided  that  the  oil  was  too 
volatile  for  the  purpose  and  that  the  results  did  not 
justify  the  expense  of  distant  shipment. 

Residual  Oil. — The  heavier  medium  grade  of  Texas 
"steamer  oil"  was  then  applied  hot  from  a  street- 
sprinkler,  the  best  results  being  obtained  at  the  highest 
temperature.  The  heating  must  be  done  with  steam 
coils  to  avoid  danger  from  fire.  The  force  employed 
consisted  of  a  foreman  and  six  laborers,  costing  $9.50 
per  day;  one  tank-wagon  and  one  street-sprinkler, 

45 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

costing  $6  per  day;  two  firemen,  costing  S3  per  day; 
and  one  ton  of  coal  at  $4;  or  a  total  of  $22.50. 
This  applied  3300  gallons  of  oil  per  day  at  seven- 
tenths  cent  per  gallon  for  application.  The  cost  of 
the  oil  will  vary  with  the  locality,  but  at  five  cents 
per  gallon  and  using  three-fourths  gallon  per  square 
yard,  the  total  cost  including  labor  equals  four  and  one- 
fourth  cents  per  square  yard.  The  results  of  applying  the 
Texas  " steamer  oil"  to  the  macadam  roads  were  good. 
The  "wearing  coat"  of  one-eighth  inch  of  road-dust 
(which  was  left  on  the  road)  was  saturated  with  the  oil 
and  made  to  cohere,  forming  a  protective  coat  of  oil- 
compacted  dust  which  tended  to  prolong  the  life  of  the 
road.  In  1908  two  and  one-half  years  later,  the  city 
engineer  of  Jackson  reported  that  the  crude  oil  and  the 
"steamer  oil"  had  left  no  appreciable  effects. 

Heavy  Residul  Oil. — The  heaviest  residual  oil,  much 
thicker  than  "steamer  oil,"  gave  the  best  results,  and 
required  heating  to  enable  it  to  flow,  working  best  when 
at  or  near  boiling-point.  When  applied  cold  it  formed 
a  thick,  sticky  mass,  which  rolled  about  on  the  road 
so  that  its  removal  was  necessary.  When  applied  hot 
the  oil  flowed  freely  from  the  tank-outlet,  was  spread 
by  hand-brooms,  and  was  absorbed  more  or  less  into 
the  road,  and  after  twenty- four  hours  was  covered  with 
sand  and  screenings;  after  four  days  it  did  not  show 
wheel- tracks.  The  macadam  roads  thus  treated  with 
oil  were  made  entirely  dustless,  and  they  could  be 
cleaned  and  swept  as  well  as  the  tarred  roads.  The 
total  cost,  as  before  itemized,  was  about  four  and  one- 
half  cents  per  square  yard. 

These  results  at  Jackson  have  been  widely  published 
and  have  been  most  useful,  forming  the  basis  for  much 

46 


OILS. 

road  work  in  many  parts  of  the  United  States.  Under 
date  of  February  25,  1908,  the  city  engineer  reported 
that  good  results  from  the  heavy  residual  oils  were  still 
apparent  after  two  and  one-half  years,  the  roads  treated 
with  them  being  still  practically  dustless. 

IN   CALIFORNIA. 

In  1906  the  city  o-f  Pasadena,  California,  following 
the  practice  which  had  proved  successful  in  Riverside, 
California,  treated  the  surface  of  new  macadam  road- 
ways with  crude  asphaltic  petroleum  containing  eighty- 
five  per  cent  of  asphaltum.  Of  this,  one  and  one-fourth 
to  one  and  one-half  gallons  per  square  yard  were  applied 
hot  to  the  protective  layer  of  sand  which  covered  the 
roadway,  forming  a  thin  carpet  or  wearing  surface  which 
makes  the  macadam  noiseless  and  dustless.  The  added 
cost  did  not  exceed  three  cents  per  square  yard.  T.  D. 
Allen,  city  engineer  of  Pasadena,  described  the  work  in 
a  paper  before  the  annual  meeting  of  the  American 
Society  of  Municipal  Improvements. 

IN   RHODE   ISLAND. 

In  1907  the  State  Board  of  Public  Roads  of  Rhode 
Island  treated  the  State  road  in  the  town  of  Barrington, 
R.  I.,  with  asphaltic  Texas  "petroleum  residuum,"  from 
the  Standard  Oil  Company's  works  at  Bayonne,  N.  J. 
One-fifth  gallon  per  square  yard  was  sprinkled  cold 
upon  the  road  with  its  normal  dust  in  place.  The  cost 
of  the  oil,  delivered  in  car,  was  four  and  six-tenths  cents 
per  gallon;  the  total  cost  of  the  treatment  including  oil 
and  labor  was  one  and  one-twentieth  cents  per  square 
yard,  or  $103  per  mile  of  sixteen-feet  roadway.  The 

47 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

results  were  satisfactory  (being  similar  to  those  already 
described  on  page  42  for  roads  in  Cranston,  R.  I.), 
and  are  detailed  by  Asst.  Engr.  Arthur  W.  Blanchard, 
Assoc.  Prof,  of  Civ.  Eng'g.  at  Brown  University,  who 
gives  valuable  information  in  his  paper  before  the  Amer. 
Assoc.  for  the  Advancement  of  Science,  with  analyses  of 
the  various  oils,  tars,  and  preparations  which  were  used 
under  his  direction.  His  opinion  is  further  quoted  at 
page  84. 

IN  ILLINOIS. 

In  1906  and  1907  part  of  the  macadamized  Sheridan 
Road  between  Chicago  and  Evanston  was  treated  with 
asphaltic  oil,  and  has  since  been  in  use  by  thousands  of 
motor-cars  daily.  Municipal  Engineering  describes  the 
conditions  on  September  16,  1906,  when  the  roadway 
was  covered  with  motor-cars.  The  oiled  portion  was  free 
from  dust  and  the  blue  sky  was  to  be  seen  through  the 
clear  air;  while  on  the  parts  not  ciled,  the  motor-cars 
disappeared  in  clouds  of  dust  which  obscured  the  sky. 
In  July,  1907,  the  oiled  portions  showed  the  effects  of 
motor-car  tires.  The  details  and  the  cost  of  the  treat- 
ment are  not  given,  but  evidently  the  effects  were  good 
but  not  lasting. 

IN    SOUTHWESTERN    STATES. 

In  a  paper  before  the  1906  meeting  of  the  American 
Society  of  Municipal  Improvements,  Walter  F.  Reichardt, 
assistant  city  engineer  of  Little  Rock,  Ark.,  stated  that 
Texas  asphaltic  oil  is  much  used,  with  good  results,  on 
the  macadam  roads  of  the  small  cities  of  the  Southwest, 
where  chert  and  trap  from  Missouri  and  Arkansas  are 

available. 

48 


OILS. 


IN   MASSACHUSETTS. 

During  1907,  a  fifteen-feet  macadam  roadway  in  Bev- 
erly, Mass.,  was  treated  with  residual  Texas  oil  containing 
twenty-seven  per  cent  of  asphalt,  sold  by  the  Gulf  Refining 
Co.  (514  Battery  Park  Building,  New  York  City),  as 
" roadbed  oil"  at  four  and  one-half  cents  per  gallon.  The 
details  of  the  treatment  were  described  at  the  November 
12,  1907,  meeting  of  the  Massachusetts  Highway  Associa- 
tion in  Boston,  by  Col.  W.  D.  Sohier  of  Beverly.  (See 
page  13.)  The  broken-stone  roadway  being  hard,  dry 
and  well-crowned,  was  swept  clean. 

Precautions. — Between  the  hours  of  10  A.M.  and  3 
P.M.  of  hot,  dry  days,  heated  oil  was  sprinkled  from  an 
ordinary  "half-moon"  sprinkling-cart  of  which  the  outer 
holes  were  plugged  so  as  to  limit  the  width  sprinkled 
to  ten  feet,  thus  avoiding  spreading  the  oil  upon  the 
edges  of  the  road  near  the  gutters.  Six  men  preceded 
and  swept  the  road  preparatory  to  the  oiling,  and  two 
men  followed  with  brooms  and  swept  and  spread  the  oil 
over  the  surface;  part  of  the  six  men  first  mentioned  also 
scattered  screened  fine  gravel  over  the  fresh  oil,  using 
one  cubic  yard  to  cover  forty  square  yards  of  surface; 
half  a  gallon  of  oil  per  square  yard  was  thus  applied 
and  covered  at  a  total  cost  including  oil  of  from  four 
to  six  cents,  or  an  average  of  four  and  one-half  cents  per 
square  yard.  Special  care  was  taken  to  avoid  oiling 
damp  or  wet  spots  where  the  oil  would  only  make  an 
oily  mud;  and  particularly  was  it  required  that  only  as 
much  road  should  be  oiled  as  could  be  covered  and  com- 
pleted before  night,  because  if  rain  came  on  the  oiled 
road  before  it  was  covered  with  fine  gravel,  the  oil  would 

49 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

float  off  and  form  an  objectionable,  oily  mass  which  must 
be  removed  from  the  roadside. 

OILED   SCREENINGS. 

At  the  same  meeting,  Charles  W.  Ross  (see  page  83), 
described  an  effective  manner  in  which  he  used  the  just- 
described  "roadbed  oil"  on  a  trap-rock  macadam  road 
in  Newton,  Mass.,  during  1907,  by  mixing  twenty  gallons 
of  hot  oil  with  one  cubic  yard  of  heated  screenings  until 
the  oil  was  thoroughly  mixed  through  the  mass,  which 
was  then  spread  with  shovels  over  a  layer  of  three-fourths 
inch  stone,  and  the  whole  then  rolled.  This  was  done 
in  June,  1907,  at  a  total  cost  of  twelve  cents  per  square 
yard,  including  stone,  screenings,  oil,  and  labor.  The 
road  was  not  watered  during  the  succeeding  five  months, 
and  there  was  no  dust,  and  it  was  satisfactory  to  a  very 
critical  community.  Mr.  Ross  further  states  that  the  oil 
sprinkled  over  the  surface  of  a  macadam  road  (at  a  cost 
of  about  two  and  one-half  cents  per  square  yard)  does  not 
save  the  road  from  wear  but  merely  stops  the  dust ;  and 
that  a  light  coating  of  sand  shaken  over  the  freshly- 
oiled  surface  was  found  to  stop  spattering  of  the  oil,  re- 
garding which  complaints  were  otherwise  made. 

IN  NEW   YORK. 

During  1906  the  State  Engineer  Department  of  New 
York  oiled  several  State  roads,  using  crude  asphaltic 
Kentucky  oil,  known  as  "Raglan  oil,"  supplied  by  the 
Standard  Oil  Company  at  four  and  three-quarter  cents 
per  gallon,  delivered  on  car,  containing  thirty  to  thirty-five 
per  cent  of  asphalt.  Five  macadam  roads  were  treated 
with  an  average  of  one-fifth  to  one-fourth  gallon  of  heated 

50 


OILS. 

oil  per  square  yard,  by  means  of  a  "White"  machine, 
at  an  average  cost  of  $128  per  mile  of  sixteen-feet  road- 
way. The  oiled  surface  was  covered  with  one-quarter 
inch  of  sand  five  hours  or  more  after  application,  pre- 
venting spattering  of  free  oil.  Dust  was  stopped  for 
some  weeks,  and  the  general  effect  seemed  satisfactory. 

CALIFORNIA   OILED   ROADS. 

Summary. — Types  of  oiled  roads  peculiar  to  California 
have  been  evolved  from  the  local  conditions  of  material 
and  climate,  as  stated  on  page  41.  The  results  have 
been  such  as  to  induce  efforts  to  adapt  the  best  of 
these  constructions  to  other  conditions  elsewhere. 

Methods. — The  best  system  is  known  as  the  "Petro- 
lithic," and  consists  in  mixing  three  and  one-half  to 
four  gallons  of  seventy  to  eighty-four  per  cent  heated 
asphaltic  oil,  with  each  square  yard  of  surface  of 
loosened,  moistened  soil  (preferably  sandy  and  surfaced 
with  gravel,  though  even  adobe  clay  is  possible),  and 
consolidating  with  a  patented  " rolling  tamper"  into  a 
firm,  smooth,  six-inch  layer,  which  is  durable  and 
dustless. 

Cost. — "  Petrolithic "  roads  have  been  built  during 
several  years  past  in  thirty  California  cities  and  their 
suburbs  at  costs  varying  from  twenty  cents  to  thirty- 
six  cents  per  square  yard,  indicating  an  estimated 
cost  of  forty-five  cents  to  fifty  cents  per  square  yard  in 
the  Eastern  States  (see  page  54).  Oiled  earth  roads  in 
the  Eastern  States,  similar  to  the  "  petrolithic "  roads, 
were  advertised  in  1908,  by  the  Imperial  Paving  Com- 
pany of  New  York  City  for  the  States  of  New  York, 
Connecticut,  and  Rhode  Island,  and  by  the  Good  Roads 

51 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

Paving  Company  of  Kansas  City,  Missouri,  for  other 
States.  The  cost  is  stated  to  be  that  of  good  macadam, 
and  the  method  uses  the  "tamping  roller,"  and  binds  the 
soil  with  liquid  asphalt  dissolved  in  crude  Kansas  or 
Texas  asphalitic  oil. 

Oiled  crushed-stone  roads  and  gravel  roads  have  also 
been  built  (see  page  56). 

Many  miles  of  rural  earth  or  sand  roads  in  California 
have  been  treated  with  one  gallon  per  square  yard  of 
forty  to  seventy  per  cent  asphaltic  crude  oil,  some  hot 
and  some  cold,  using  a  grader  and  a  drag,  at  one-twelfth 
of  the  above  cost,  or  $150  per  mile  (see  page  55). 

SUBSTITUTES. 

It  is  probable  that  similar  results  may  elsewhere  be 
had  with  the  residuum  of  other  asphaltic  oils,  or  with 
coal-tar  preparations  like  "tarvia"  (page  74).  It  may 
be,  also,  that  commercial  asphaltum  derived  from  Cali- 
fornia oil  may  be  liquified  with  about  forty  per  cent 
of  Texas  or  Kansas  crude  oil,  so  as  to  be  like  the 
California  oil.  But  nature's  combinations  are  difficult 
to  imitate — it  is  not  always  possible  to  tell  by  analysis 
why  one  oil,  or  tar,  succeeds  and  another  fails;  and 
such  efforts  to  imitate  California  oils  are  as  yet  experi- 
mental (see  page  39). 

The  "White"  machine  for  sprinkling  oil  is  generally 
used,  as  described  on  page  88. 

PETROLITHIC   PAVEMENT. 

Methods. — The  following  describes  the  best  "Petro- 
lithic"  pavement:  The  roadway  is  properly  formed  and 
rolled,  when  dry,  until  solid,  and  all  depressions  are 

52 


OILS. 

filled  and  tamped.  The  surface  is  then  ploughed  to  a 
depth  of  six  inches  and  the  loosened  earth  or  sand  thor- 
oughly pulverized  by  repeated  passages  of  cultivator  or 
harrow,  and  all  stones  of  two  inches  diameter  and  larger 
removed.  The  roadbed  is  then  sprinkled  with  sufficient 
water  to  evenly  dampen  the  top  four  inches  and  this 
depth  is  then  worked  with  a  lightly-set  cultivator  to 
loosen  and  mix  the  earth  and  water  to  a  uniform  damp- 
ness. 

Oiling. — Upon  this  damp  surface  is  then  sprinkled 
crude  oil  containing  not  less  than  sixty-six  per  cent  of 
soft  "D"  grade  asphalt,  nor  over  two  per  cent  of 
water,  the  oil  being  heated  to  not  less  than  100°  F. 
nor  over  190°  F.,  and  being  evenly  spread  at  the  rate 
of  one  gallon  per  square  yard  of  surface.  This  is 
then  thoroughly  cultivated  ten  times,  or  until  well 
mixed  to  a  depth  of  four  inches.  A  second  similar 
coat  of  oil  is  then  spread  and  turned  to  a  depth  of 
four  inches  in  the  same  way,  until  the  oil  and  the 
soil  are  well  mixed;  going  over  it  with  a  cultivator  at 
least  ten  times  after  each  coating  or  until  every  particle 
of  soil  is  coated  with  the  oil.  It  is  then  ploughed 
four  inches  deep  with  a  plough  that  thoroughly  turns 
the  furrows. 

Tamping. — The  " rolling  tamper"  is  then  applied, 
beginning  the  tamping  at  six  to  seven  inches  depth 
and  tamping  solidly  upward  to  within  two  inches  of  the 
top.  The  surface  is  then  evenly  covered  (if  gravel  is 
available)  with  two  inches  of  hard  gravel,  one-quarter 
inch  to  one  and  one-half  inches  in  size,  and  this  is 
thoroughly  mixed  by  cultivator,  with  the  top  loose  two 
inches  of  the  oiled  soil,  using  care  meantime  not  to 
disturb  the  tamped  base.  There  is  then  spread  over 

53 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

the  gravel  surface  one  and  one-half  gallons  of  the 
same  hot  oil  per  square  yard,  and  the  whole  again 
tamped  with  the  rolling  tamper  until  the  entire  surface 
is  uniformly  hard  and  solid;  an  ordinary  ten-ton  roller 
is  then  used  to  smooth  the  surface. 

The  "rolling  tamper"  mentioned  is  a  peculiar  and  pa- 
tented horse-drawn  roller,  manufactured  and  sold  by 
the  Petrolithic  Pavement  Company  of  Los  Angeles, 
California,  at  $750  f.  o.  b.  cars.  It  is  about  eight  feet 
long  and  five  feet  in  diameter,  weighs  about  5000  pounds, 
and  is  made  in  two  sections  for  ease  in  turning  around. 
The  outer  surface  is  studded  with  iron  legs,  each  pro- 


ROLLING  TAMPER. 

jecting  seven  inches,  the  outer  end  of  each  leg  being  like 
a  sheep's  foot,  about  two  inches  by  three  inches.  There 
are  fifteen  of  these  legs  in  each  of  twelve  rings,  or  180 
in  all,  and  they  are  forced  into  the  pulverized  and  oiled 
earth  and  gravel  by  repeated  passages  over  the  road  until 
it  is  packed  to  the  top,  so  that  the  feet  ride  upon  the 
hardened  surface.  Should  excess  of  oil  then  appear,  suffi- 
cient clean,  sharp,  coarse  sand  to  absorb  the  oil  is  spread 
over  the  oily  surface,  which  is  then  rolled  until  solid. 

Cost. — With  oil  costing  seventy-two  cents  per  barrel  of 
forty-two  gallons,  such  roads  have  cost  an  average  of 

54 


OILS. 

twenty  cents  per  square  yard,  varying  up  to  thirty-six 
cents  per  square  yard  with  the  conditions  and  cost  of 
oil.  Such  roads  have  been  successfully  built  in  Los 
Angeles  upon  adobe  clay,  which  is  a  most  difficult 
material. 

OILED   RURAL   ROADS. 

Cheaper  and  simpler  construction  has  been  used  to 
make  a  thousand  or  more  miles  of  oiled  country  roads,  as 
described  by  the  California  State  Highway  Commissioner, 
N.  Ellery.  The  earth  road  being  properly  drained, 
formed,  crowned,  and  made  solid,  each  square  yard  of 
its  surface  is  sprinkled  with  one  gallon  of  cold  crude 
asphaltic  oil  having  at  least  forty  per  cent  of  asphaltum, 
or  more,  if  such  is  obtainable;  this  to  be  determined  by 
tests  as  detailed  on  page  38.  If  it  contains  more  than 
forty  per  cent,  heating  will  be  necessary  to  give  fluidity. 
As  soon  as  the  oil  is  spread  over  the  roadbed  it  is  covered 
at  once  with  four  inches  of  earth  from  the  roadside,  or 
preferably  with  sand  or  fine  gravel,  if  obtainable.  It  is 
then  compacted  by  rolling  with  an  ordinary  roller,  horse- 
drawn  or  steam-driven,  using  a  grader  and  a  drag  to 
keep  the  road-surface  smooth,  until  the  oil  eventually 
comes  to  the  surface  as  the  material  packs  under  rolling 
and  use,  oily  spots  being  meantime  covered  with  sand. 
This  treatment  is  said  to  be  given  at  a  cost  of  one  and 
one-half  cents  per  square  yard,  or  $150  per  mile;  but 
it  is  evident  that  this  figure  must  be  increased  if  much 
rolling  is  done.  It  requires  to  be  followed  by  frequent 
and  careful  use  of  the  grader  and  drag,  and  many  such 
roads  have  failed  for  lack  of  this  care.  When  well  built 
and  maintained,  the  effect  is  to  reduce  the  dust  and 

55 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

improve  the  road;  but  of  course  these  cheap  roads  are 
in  no  way  to  be  compared  with  the  "  Petrolithic "  roads 
before  described,  nor  with  the  hard  gravel  or  stone 
roads  used  elsewhere.  If  the  natural  earth  roadbed  is 
of  alkali  soil,  other  soil  must  be  spread  over  it,  as  alkali 
disintegrates  the  asphalt  in  the  oil. 

Oiled  gravel  roads  are  also  used  in  California,  and 
Commissioner  Ellery  describes  their  construction.  Upon 
the  formed  sub-grade  compacted  by  the  usual  wetting 
and  rolling,  there  is  spread  the  coarser  portion  of  screened 
gravel,  four  to  five  inches  deep.  This  is  rolled  with  a 
ten-ton  roller,  and  one  gallon  of  oil  having  forty  per 
cent  or  more  of  asphalt  is  applied  per  square  yard  of 
surface.  This  is  at  once  covered  with  three  inches  of 
the  finer  portion  of  the  screened  gravel  and  rolled  until 
compact,  the  oil  tending  to  work  upward  into  this  top 
layer  as  it  packs. 

Oiled  broken-stone  roads  are  similarly  made,  with  the 
usual  base  course  of  four  to  six  inches  of  the  one  and  one- 
quarter  inch  to  two  and  one-half  inches  of  loose,  crushed 
rock,  which  is  sprinkled  with  water  and  rolled  in  the 
usual  way.  On  this,  when  dry,  there  is  sprinkled  one 
gallon  of  heated,  heavily  asphaltic  oil  per  square  yard 
of  surface,  which  is  at  once  covered  with  two  inches  of 
three-quarter  inch  to  one  and  one-half  inches  crushed 
rock  over  which  there  is  spread  one  inch  of  screenings 
of  the  same.  The  road  is  then  rolled  thoroughly  with 
a  ten-ton  roller  until  the  oil  shows  in  the  screenings. 
Where  oil  comes  to  the  surface  the  spots  must  be 
covered  with  more  screenings.  In  the  case  of  either 
gravel  or  broken-stone  roads  thus  oiled,  the  added 
cost  is  that  of  the  oil  and  its  heating,  less  the  saving 
in  water. 

56 


OILS. 


REPAIRS   OF   OILED   ROADS. 

All  oiled  roads  need  close  attention  and  prompt  re- 
pairs. Ruts  and  weaks  spots  must  be  cut  out,  leaving 
vertical  sides;  the  cut  must  then  be  filled  with  the 
material  of  the  road, — sand,  or  fine  gravel  or  fine  stone, 
as  the  case  may  be, — mixed  with  oil.  This  added 
material  must  be  slightly  higher  than  the  surrounding 
surface,  after  oil  has  been  poured  upon  it,  and  it  has 
been  thoroughly  packed  with  a  hand-tamper. 

Oiled  roads  thus  built  and  cared  for  in  California  have 
proved  to  be  great  improvements  upon  their  former  con- 
ditions, and  to  be  comparatively  dustless.  The  careless- 
sprinkling  of  California  asphaltic  oil  on  unformed  and 
uncared-for  country  roads  has  often  been  tried  and 
found  to  be  useless,  as  noted  on  page  39. 

OILED    SAND   ROAD   IN   MASSACHUSETTS. 

Methods.— In  1905  and  1906  the  Massachusetts  High- 
way Commission  oiled  a  common  sand  road  in  the 
town  of  Eastham  (on  Cape  Cod,  where  there  is  no 
stone  available),  using  a  heavy  Texas  residual  oil 
containing  sixty-five  per  cent  of  asphalt.  Two  appli- 
cations, each  of  three-quarters  gallon  per  square  yardy 
were  made  in  1905  and  one  in  1906.  The  oil  was 
heated  to  180°  F.,  and  was  spread  from  a  watering-cart 
with  special  sprinkler.  Two  weeks  after  the  first  coat,, 
the  second  was  applied,  and  the  whole  oiled  surface  was 
then  thoroughly  chopped  up  with  a  disc  harrow,  rolled 
with  a  light  horse-drawn  roller  and  then  covered  with 
sand.  Thin  sprinklings  of  sand  were  added  from  time 

57 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

to  time  to  cover  oil  which  came  to  the  surface.  The 
results  were  generally  satisfactory  and  the  road  in  1908 
was  in  good  condition  after  two  years  of  use.  The  total 
cost  for  the  two  years  of  treatment,  exclusive  of  shaping, 
grading,  drainage,  and  stone,  etc.,  was  twenty- two  and 
one-fifth  cents  per  square  yard,  or  $2083  per  mile  of 
sixteen-feet  roadway.  The  Commission  believes  that 
oil  can  be  used  to  advantage  on  a  road  of  this  kind  where 
the  roadbed  is  of  loose  sand,  the  drainage  good,  the 
traffic  light,  and  the  cost  of  more  permanent  materials 
is  high.  Frost  appears  to  have  had  no  ill  effect  upon  it. 

SURFACE    TREATMENTS. 

"  Asphaltoilene"  is  the  trade  name  of  a  prepared 
residuum  of  Kentucky  asphaltic  oil,  being  a  black,  heavy 
oil  which  looks  like  tar,  and  consists  of  sixty  per  cent 
to  sixty-five  per  cent  of  pure  asphalt  dissolved  in  and 
carried  by  enough  petroleum  to  make  it  fluid,  thus  serving 
as  a  vehicle  to  deposit  the  contained  asphalt  upon  the 
road-surface  where  the  petroleum  is  absorbed  or  evap- 
rates. 

Method  and  Cost. — It  has  probably  been  more  used  in 
the  Middle  and  Eastern  States  than  any  other  one  form 
of  residual  asphaltic  oil,  and  gives  good  results  when 
properly  applied,  in  warm  weather,  to  the  dry  surface 
of  clean,  hard,  well-drained,  well-crowned,  crushed-stone 
roads.  There  is  no  expense  for  sand  or  screenings  to 
be  spread  over  it.  Asphaltoilene  is  prepared  and  used 
by  the  Road  Improvement  Company  of  Cincinnati, 
Ohio,  which  company  contracts  for  the  completed  sur- 
face at  varying  prices,  averaging  about  four  cents  to 
six  cents  per  square  yard.  It  is  applied  hot  from  a 

58 


OILS. 

" White"  machine,  which  distributes  it  by  gravity  evenly 
and  in  regulated  quantity,  forming  a  finished  surface 
which  is  elastic,  pliable,  smooth,  and  waterproof,  and 
it  is  claimed  that  this  surface  is  maintained  under 
heavy  traffic  by  two  applications  the  first  year  and  one 
each  succeeding  year. 

Extent  of  Use.— During  1906  and  1907,  there  have 
been  thus  treated  roads  in  and  near  various  cities, 
among  them,  Louisville,  Kentucky;  Cincinnati,  Ohio; 
Detroit,  Michigan;  and  Newton,  Massachusetts.  In 
Detroit,  the  West  End  Boulevard  was  coated  with 
asphaltoilene  in  July,  1906,  and  has  since  served  as 
the  testing  speedway  for  ten  motor-car  factories,  as 
well  as  for  pleasure.  It  is  said  that  over  500  motor- 
cars travel  it  every  day,  and  at  high  speed,  and  that 
its  surface  is  dustless  and  good. 

At  Newton,  Mass. — Asphaltoilene  was  applied  to 
macadam  roads  in  Newton,  Mass.,  in  1907,  under 
direction  of  Charles  W.  Ross,  highway  commissioner, 
who  considered  the  results  very  satisfactory.  The  heat- 
ing was  necessarily  done  by  steam  and  not  by  direct 
heat.  When  spread  by  a  " White"  machine  on  the  road, 
it  looked  like  tar,  and  required  several  days  to  soak  into 
the  road.  It  then  was  perfectly  smooth  and  hard  and 
had  the  appearance  of  black  india  rubber.  If  the  road 
is  well  swept  and  thoroughly  rolled  to  a  smooth,  hard 
surface  before  application,  the  results  are  good.  The 
cost  in  Newton  was  six  cents  per  square  yard. 

"  Asphaltoilene "  seems  to  closely  resemble  the  heavily 
asphaltic  oils  of  California,  and  to  accord  with  the 
suggestion  on  page  52. 

"Asphaltine"  is  another  preparation  of  asphaltic 
residuum,  which  is  made  in  Geneva,  Switzerland,  where 

59 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

it  is  used  on  macadam  roads  in  the  vicinity  with  good 
effect.  It  is  a  mixture  of  the  asphaltic  residuum  from 
the  petroleum  of  Galicia,  Austria,  with  mazout,  which 
is  a  French  by-product  of  petroleum  refining.  The  mix- 
ture is  used  hot  or  cold,  but  the  former  gives  the  best 
results.  The  average  cost  in  Geneva  is  about  three 
cents  per  square  yard,  including  labor  of  heating  and 
spreading. 

OILS    DERIVED    FROM   GAS   MANUFACTURE. 

Summary.— "Oil-tar,"  "tar-oil,"  "oil- gas -tar,"  "water- 
gas-tar"  are  several  names  for  a  substance  much  used 
on  English  roads  (and  known  as  "odocreol"  in  France 
and  Italy),  which  is  a  by-product  of  the  manufacture 
of  carburetted  water-gas  (used  to  enrich  coal-gas)  from 
the  asphaltic  residuum  of  Russian  petroleum,  known  as 
"solar-oil"  or  other  similar  residuums. 

"Creosote-oil"  is  a  distillate  from  the  coal-tar  which 
is  condensed  during  distillation  of  coal-gas  from  bitu- 
minous coal. 

COMPOSITION. 

Substances  known  commercially  by  each  of  these 
names  vary  as  widely  in  composition  and  character  as 
do  the  materials  from  which  they  are  derived,  and  espe- 
cially as  the  treatments  of  these  materials  vary.  It  is 
sometimes  difficult  because  of  these  variations  to  account 
for  success  or  failure  in  their  use  on  roads. 

"Oil-gas-tar"  one  of  its  several  names,  is  a  brown- 
black  liquid  having  the  odor  and  appearance  of  coal- 
tar,  except  that  its  greater  fluidity  permits  its  distribu- 

60 


i  t 


OILS. 

tion  from  a  sprinkler,  without  heating.  Its  specific 
gravity  is  about  1.04.  Its  composition  is  about  as  follows 
(see  table  on  page  86): 

Light      oils,  volatile  from    70°  F.  to  170°  F 11.2  per  cent 

Medium  "         "         "     170   "    "  230  " 22 

Heavyoils,          "         "     230   "    "  260   " 16 

Anthracene,         ' '    above  260   ' '    '  *  42 

Water,  3  per  cent;  loss,  5.8  per  cent;  8.8 

100.  o 


METHODS. 

It  may  be  applied  cold,  as  it  is  exceptionally  penetrating 
and  abates  dust  well,  but  it  requires  several  coats  to  give 
results.  It  is  most  effective  when  applied  hot;  in  either 
case  the  road-surface  must  be  thoroughly  cleaned  and 
put  in  good  condition.  It  has  usually  been  applied  from 
hand-sprinklers,  repeating  the  coating  until  the  surface 
is  filled.  The  protective  asphaltic  skin  which  quickly 
forms,  prevents  dust  and  is  not  much  affected  by  light 
traffic  which  need  not  be  interrupted  during  application, 
nor  by  rain  which  may  come  soon  after  it  has  soaked  into 
the  road,  which  it  does  quickly.  But  it  does  not  endure 
heavy  traffic  and  it  does  not  resist  heavy  rains.  Its 
advantages  over  coal-tar  are  that  it  can  be  applied  more 
quickly,  without  interruption  of  traffic,  and  at  less  cost, 
which  has  been  about  one  cent  for  the  first  coat  and  less 
for  following  coats,  of  which  two  or  more  may  be  required 
to  constitute  one  application.  Its  duration  is  not  great 
under  traffic,  and  it  can  only  be  considered  as  being  one 
of  the  best  of  the  dust  palliatives,  and  it  has  been  ex- 
tensively so  used  both  in  England  and  in  France. 

61 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


CREOSOTE-OIL. 

"Creosote-oil"  distilled  from  coal-tar,  resembles  coal- 
tar  somewhat  in  appearance  and  has  a  characteristic 
objectionable  odor.  Mixed  with  resin,  and  mixed  with 
tallow,  and  also  alone,  it  was  used  on  Liverpool  roads  in 
competitive  tests  in  1902  and  1903,  and  was  then  consid- 
ered to  give  better  results  than  any  others  of  a  number 
of  dust  preventatives  which  were  tried  (page  43).  One- 
eighth  gallon  per  square  yard  was  applied  with  hand- 
watering  cans  and  with  syringes.  Time  was  required 
for  its  absorption,  and  therefore  one-half  of  the  width 
of  the  road  was  treated  at  a  time,  so  that  rubber-tired 
vehicles  could  meantime  use  the  other  half.  The  con- 
clusion of  the  tests  was  that  creosote-oil  was  cheapest 
and  most  enduring.  The  dust  was  laid  by  it,  and 
there  was  marked  reduction  in  the  wear  of  the  mac- 
adam road-surface  as  shown  by  the  reduced  sweepings. 

CONCLUSION. 

Further  experience  has  shown  the  greater  durability 
and  efficiency  of  refined  coal-tar  in  preference  to  this 
derivative. 


62 


COAL-TAR  PREPARATIONS. 


SUMMARY. 

Refined  coal-tar,  produced  in  gas  manufacture  and 
treated  to  remove  its  injurious  parts  and  yet  to  preserve 
its  ductility  and  to  secure  uniformity,  has  been  generally 
accepted  by  the  road  authorities  of  France  and  England , 
and  also  by  those  road-engineers  in  the  United  States 
who  have  given  the  subject  most  attention,  as  being  the 
material  with  which  to  improve  broken-stone  roads; 
binding  the  surface  of  existing  roads  and  bettering  the 
construction  of  new  roads,  thereby  preventing  the 
formation  of  road  dust. 

HEATING. 

In  the  several  following  descriptions  of  heated  tar 
applications,  the  desirable  degree  of  heat  is  mentioned 
in  each  case,  but  in  actual  practice  it  is  most  difficult  to 
regulate  this  closely.  Even  when  thermometers  are  put 
into  the  tar  to  test  it,  there  is  no  means  of  knowing  the 
temperature  at  the  bottom  of  the  kettle  where  it  may 
vary  quickly,  especially  when  a  wood  fire  is  used  for  the 
heating.  In  many  cases  where  road-tarring  has  failed, 
this  is  no  doubt  a  result  of  thus  overheating  the  tar. 

63 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

Kettles. — In  some  of  the  1906  experimental  work  of 
road-tarring  in  New  York,  the  wheeled  tar-kettles  were 
of  seventy-five  gallons  capacity  each,  and  a  continuous 
supply  of  hot  tar  was  secured  by  keeping  a  barrel  of  tar, 
or  tarvia,  emptying  into  the  kettle  at  about  the  same 
rate  that  the  hot  tar  ran  from  it  onto  the  road. 

In  the  1907  Massachusetts  work  at  Westwood,  Wayland, 
and  Weston,  the  kettles  used  were  of  five-hundred  gallons 
capacity  each,  giving  better  protection  from  over-heating. 
They  had  wood-burning  grates  covering  the  entire  kettle 
bottom,  and  also  arrangements  to  have  two  barrels,  and 
sometimes  three  barrels  of  tar  emptying  into  the  kettle 
while  the  hot  tar  ran  out;  but  this  latter  feature  was  not 
much  used.  For  suggested  improvements,  see  page  119. 

Steam-coils. — In  any  case  where  direct  fire  is  used  to 
heat  the  tar,  there  is  danger  of  overheating  and  of  the 
consequent  failure  of  the  work.  To  avoid  this  steam- 
heated  coils  should  be  used  when  possible. 

UNIFORMITY. 

For  success  in  such  use  of  tar,  its  quality  is  most  im- 
portant (see  page  71).  If  it  is  heated  too  much  and 
"refined"  too  far,  it  becomes  brittle  and  makes  black 
dust.  If  not  refined  enough,  the  light  oils  and  ammo- 
niacal  liquors  will  disintegrate  it.  A  reliably  uniform 
product  is  essential.  This  requirement  is  supplied  by 
" tarvia"  in  the  United  States  and  by  "Clare's  patent 
tar  compo"  in  England,  and  doubtless  by  others. 

Good  tar,  properly  applied,  is  the  cheapest  and  best 
lorm  of  dust-preventer  and  road-saver,  being  more 
effective  and  durable  than  any  other  now  known. 


64 


COAL-TAR  PREPARATIONS. 


OPINIONS. 

Massachusetts. — In  accord  with  this  is  the  statement 
of  Division  Engineer  Franklin  C.  Pillsbury,  of  the 
Massachusetts  Highway  Commission,  made  to  the 
November,  1907,  meeting  of  the  Massachusetts  High- 
way Association  that,— 

"  The  Commission  concludes  that,  for  the  present,  tarviating  (or 
treating  with  prepared  coal-tar)  is  the  best  method  now  known  for 
protecting  the  surface  of  macadam  roads," 

This    decision    was    reached    after   a  year   of   use  and 
observation  of  results  on  Massachusetts  roads. 

England. — This  also  accords  with  the  opinion,  in 
August,  1907,  of  Thomas  Aitken,  M.  Inst.  C.  E.,  a 
recognized  English  authority  on  road-construction  and 
author  of  "  Road-making  and  Maintenance,"  who 
says : 

"There  can  be  no  doubt  that  the  building-up  of  the  road-stone 
coating  with  a  matrix  of  refined  tar,  chips  and  dust  as  a  binding 
medium,  is  the  best  possible  method  of  solving  the  dust  problem  in 
a  satisfactory  and  permanent  manner. "  (This  refers  to  the  results 
of  forcing  a  fine  spray  of  coal-tar  into  the  road-material,  rather  than 
spreading  the  tar  over  the  surface  and  trusting  to  absorption.) 
See  page  89. 

France. — French  road-engineers  also  express  the  same 
opinions  in  the  Annales  des  Fonts  et  Chausses  after 
four  years  of  experience  in  tarring  broken-stone  roads 
under  their  charge.  M.  Heude,  chief  engineer  of  the 
department  of  the  Seine  and  Marne,  and  M.  Sigault, 
M.  Girardeau,  M.  Arnaud,  and  M.  Vahheur,  city  engi- 
neer of  Paris,  all  substantially  agree  that  tarring  has 
been  shown  to  be  a  practical  means  of  preventing 

65 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

dust  in  summer  and  mud  in  winter,  and  that  the 
saving  exceeds  the  cost,  and  that  future  new  roads 
will  be  tarred.  The  general  acceptance  in  France  of 
these  opinions  is  further  evidenced  by  the  announce- 
ment that  "the  use  of  coal-tar  and  its  derivatives  will 
be  given  special  prominence  in  the  programme"  of 
the  International  Road  Congress,  organized  by  the 
French  Minister  of  Public  Works,  to  meet  in  Paris  in 
October,  1908  (see  page  16). 

United  States. — Logan  Waller  Page,  Director  of  the 
United  States  Office  of  Public  Roads  at  Washington, 
D.  C.,  states  on  April  20,  1908,  regarding  an  application 
of  crude  tar,  in  August,  1905,  that  the  results  after 
two  and  one-half  years  are  still  good  on  portions  of 
the  roads,  and  on  the  whole  have  been  satisfactory, 
the  roads  so  treated  being  still  noticeable  for  the 
absence  of  mud  and  dust.  This  refers  to  work 
done  by  the  office  at  Jackson,  Tennessee,  where 
an  old  macadam  road  (of  non-absorbent  novaculite 
crushed  rock),  on  the  main  business  street,  was  treated 
with  crude  coal-tar  from  Alabama  coke,  at  the  rate  of 
forty-five  one-hundredths  gallon  per  square  yard.  The 
tar  was  heated  to  160°  to  190°  F.,  and  was  applied 
through  a  flatted,  one-inch  nozzle,  and  spread  with 
brooms,  during  hot,  dry  weather. 

Other  opinions  are  given  in  connection  with  following 
descriptions  of  actual  works. 


66 


COAL-TAR  PREPARATIONS. 


CONDITIONS. 

Success  depends  upon— 

The  quality  of  the  tar,  which  must  be  the  best  possible ; 

The  state  of  the  weather,  which  must  be  clear  and 
warm; 

The  condition  of  the  road-surface,  which  must  be 
clean  and  dry; 

The  manner  of  application,  which  must  be  rapid  and 
complete. 

OBJECTIONS. 

Too  much  tar  on  the  surface  will  be  worse  than  the 
former  mud  and  dust,  being  sticky  when  warm  and 
slimy  when  wet.  These  objections  are  avoided  when 
the  tar,  either  cold  or  hot,  is  forced  in  a  fine  spray  into 
the  minute  voids  and  spaces  between  the  stone  fragments, 
by  means  of  pneumatic  pressure  from  a  "  tar-sprayer," 
by  which  the  quantity  and  the  distribution  are  made 
uniform,  and  small  pools  of  tar  are  not  left  on  the 
surface. 

TAR- SPRAYING. 

Such  a  tar-sprayer  must  work  so  rapidly  that  full 
advantage  can  be  taken  of  warm,  dry  weather,  during 
which  to  treat  one-half  of  the  width  of  several  miles 
of  road  per  day. 

Four  kinds  of  such  machines  are  made  and  used  in 
England  and  one  or  more  in  France,  as  described  on 
pages  69  and  89. 

The  application  of  tar  by  forcing  a  fine  spray  into  the 
body  of  the  road  is  too  recent  to  predict  the  endurance 

67 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

of  a  broken-stone  road  so  treated;  but  the  most  con- 
servative opinion  of  road-builders  experienced  in  this 
work  is  that  such  roads  will  last  at  least  twice  as  long 
as  formerly,  and  that  meantime  there  will  be  a  con- 
siderable annual  saving  in  the  decreased  cleaning  and 
repairing.  At  the  least,  this  means  less  cost  and  less 
dust. 

FAILURES. 

There  have  been  many  failures  in  using  tar  on 
roads,  both  in  original  construction  and  in  surface 
treatment,  or  "painting."  Some  have  been  caused  by 
the  poor  quality  of  the  tar  as  detailed  on  page  7 1 .  Some 
have  resulted  from  careless  methods,  some  from  ex- 
cessive traffic,  and  some  from  unexplained  causes. 

In  New  York. — One  conspicuous  piece  of  road  which 
was  treated  with  tarvia  in  1906  was  more  or  less  a 
failure,  because  no  attempt  seemed  to  have  been  made 
to  dry  damp  spots  in  shaded  portions  nor  to  put  the 
road  in  proper  condition  before  application. 

In  Massachusetts. — Another  case  is  in  the  city  of 
Springfield,  Mass.,  where  half  a  mile  cf  macadam 
roadway,  on  a  four  and  one-half  per  cent  grade,  was 
tarviated  in  1906.  It  is  stated  by  Arthur  A.  Adams, 
superintendent  of  streets,  that  the  tar,  which  had 
apparently  been  properly  applied,  had  entirely  disap- 
peared within  a  year,  under  heavy  traffic. 

There  are  no  doubt  other  failures,  but  the  general 
opinion  of  users  is  favorable.  One  disadvantage  of 
tar-painting  with  crude  tar,  is  that  a  road  recently  so 
treated  sometimes  has  a  coat  of  black,  slimy  mud, 
when  frost  and  snow  are  succeeded  by  continuous 
rain;  and  such  mud  is  difficult  to  remove. 

68 


COAL-TAR  PREPARATIONS. 
HISTORY. 

The  use  of  coal-tar  in  the  original  building  of 
broken-stone  roads  is  no  new  thing,  it  having  been  so 
used  in  Nottingham,  England,  in  1840,  and  more  or 
less  throughout  England  and  France  for  thirty  years  or 
more;  and  also  in  the  United  States.  But  its  application 
to  the  surface  of  an  existing  macadam  road  was  first 
made  in  France  at  Sainte-Foy-la-Grande,  near  Bordeaux, 
unsuccessfully,  in  1880;  and  next  at  Melbourne,  Australia, 
in  1886,  where  the  macadam  was  first  put  in  good, 
firm  condition,  and  refined  coal-tar  was  then  spread  upon 
it,  and  was  covered  with  screenings  of  crushed  stone. 
The  results  were  so  good  that  the  method  has  since 
been  continued  there. 

It  was  next  used  for  this  purpose  byM.  Girardeau, 
of  Fontenay-le-Comte,  road  commissioner  of  the  depart- 
ment of  the  Vendee  in  France,  in  1896,  on  the  State  road 
from  Lucon  to  Pointe  de  1'Aiguille.  The  results  led  to 
other  tests  in  various  parts  of  the  great  national  road 
system  of  France,  and  in  1898  it  was  discovered  that  by 
applying  the  tar  hot,  it  then  better  penetrated  the  road 
(being  thus  made  thin  like  water),  and  that  it  cemented 
the  road  dust  between  the  fragments  of  stone,  which 
thus  were  held  in  a  plastic  but  firm  matrix. 

TAR-SPRAYING   MACHINES. 

The  tar  treatment  of  road  surfaces  was  then  adopted 
in  England,  and  inventors  there  and  in  France  devised 
various  machines  for  increasing  the  speed  and  decreas- 
ing the  cost  of  application,  which  were  mainly  accom- 
plished by  forcing  the  tar,  either  cold  or  hot,  by  pneumatic 
pressure  through  spraying-nozzles,  giving  rapid  and 

69 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

uniform  flow  and  distribution  without  the  need  of  hand- 
sweepers.  Those  machines  which  are  able  to  spray  tar 
which  is  cold,  thereby  avoid  the  considerable  expense 
and  trouble  of  heating  it.  The  heat  is  so  quickly  lost 
that  it  is  of  little  effect  after  the  tar  is  spread. 


TESTS. 

A  competitive  trial  of  these  machines  was  held  by 
the  English  Roads  Improvement  Association,  acting 
with  the  Motor  Union  and  the  Royal  Automobile  Club, 
May  22  to  27,  1907,  at  Reading,  in  Berkshire  County, 
England,  where  there  were  present  road-engineers  and 
representatives  of  motor-car  associations  from  all  parts 
of  Great  Britain,  as  well  as  from  France,  Germany, 
Italy,  and  Egypt.  Eight  machines  and  thirteen  mate- 
rials were  tested  by  actual  use,  though  the  roads  and 
weather  were  not  dry  enough  for  best  results.  Six 
months  later,  when  the  results  of  the  work  were 
known,  the  judges  awarded  two  prizes,  and  made 
mention,  in  the  order  named: 

First: — "Aitkens     Pneumatic     Tar-sprayer,"     two 

sizes,  hot  or  cold  tar  under  pressure. 
Second: — "Tarspra,"    three   sizes,   hot   or  cold   tar 

under  pressure. 

Third:— "  Johnston-Lassailly     Patent     Tar     road- 
binder,"    hot    tar    by   gravity,   spread   by   automatic 

trailing  brushes. 
Fourth: — "Thwaite    anti-road    dust    system,"    hot 

tar  under  pressure. 
Fifth: — "Tarmaciser,"     steam    traction-engine     to 

clean  road;    heat  and  apply  tar  and  cover  and  roll. 

Each  of  these  is  described  on  pages  89-97. 

70 


COAL-TAR  PREPARATIONS. 

The  three  first  named  are  each  very  effective,  having 
done  much  good  work  in  England  or  France,  or  both. 
It  is  said  in  London  that  their  best  features  may  yet 
be  combined  in  one  machine.  None  are  yet  used  in 
the  United  States,  where  distribution  is  still  made  by 
slow  gravity  flow,  usually  requiring  that  the  tar  be 
heated  and  be  spread  by  hand-brooms,  at  high  cost  for 
labor,  and  at  a  rate  of  progress  about  one-twentieth  of 
that  at  which  better  work  is  done  in  Europe. 

COAL-TAR    QUALITY. 

It  has  come  to  be  recognized  since  1905  that  "  coal- 
tar"  is  a  very  indefinite  term,  and  that  the  products 
of  different  gas-works  vary  widely  with  the  kinds 
of  coal  used  and  the  methods  of  treatment,  each  of 
which  is  frequently  changed,  even  at  the  same  gas 
works.  This  knowledge  has  led  to  careful  tests  and 
analyses  of  different  types  of  coal-tar  to  determine,  if 
possible,  why  some  succeeded  and  others  failed  in  road 
work.  This  induced  treatment  by  experts  to  remove 
objectionable  components  and  those  which  would  be 
soluble  in  rain-water,  and  to  add  desirable  ones  which 
might  increase  fluidity  or  add  to  the  permanence  of 
ductility  and  adhesiveness,  which  should  be  such  that 
after  boiling,  the  coal-tar  may  be  drawn  out  in  long 
threads.  Many  failures  which  had  formerly  occurred 
were  explained  by  the  former  omission  of  such  tests 
and  absence  of  such  qualities.  It  is  recognized  that 
most  road  engineers  lack  the  time  and  equipment  to 
analyze  each  lot  of  tar,  or  to  interpret  the  results  of 
such  tests,  which  are  at  best  costly  and  uncertain  and 
are  of  little  general  utility  with  the  present  knowledge  of 
the  subject. 

71 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

There  can  be  no  successful  system  of  tarring  road 
unless  there  is  available  a  uniform  standard  and  a  reliable 
supply  of  refined  tar.  The  lack  of  these  in  England 
accounts  for  many  failures,  and  has  so  far  prevented  the 
universal  use  which  would  be  expected  from  knowing 
of  the  many  successes. 


SPREADING  TARVIA  FROM  A  SLOTTED  SPRINKLER  (Pittsburg,  Pa.). 


VARIATIONS. 

Every  city  has  its  gas-works,— often  several  of 
them, — each  using  various  grades  cf  coal,  and  fre- 
quently changing  their  methods  of  treatment  to  make 
gas.  Even  when  these  features  are  constant,  the 
quality  of  crude  tar  from  a  given  supply-tank  will 
vary  as  the  quantity  in  the  tank  varies,  the  tar  drawn 
from  the  bottom  of  a  full  tank  sometimes  differing 
materially  from  that  drawn  when  the  same  tank  is 
nearly  empty.  The  resulting  crude  coal-tars  are  there- 

72 


COAL-TAR  PREPARATIONS. 


fore  produced  in  great  variety,  so  that  road-construc- 
tion which  succeeds  at  one  time  may  fail  at  another. 
Most  failures  have  resulted  from  using  poor  tar. 


UNIFORMITY. 

The  need  for  uniformity  is  met  in  the  United  States 
by  a  prepared  refined  coal-tar,  widely  known  as 
"Tarvia,"  which  has  been  used  and  commended  by 
the  United  States  Office  of  Public  Roads  at  Wash- 
ington, and  by  the  Massachusetts  Highway  Commis- 
sion (page  65),  and  by  many  city  and  road  engieners 
throughout  the  United  States  and  Canada,  where  one 
million  square  yards  were  tarviated  during  1906  and 
three  millions  in  1907.  It  is  supplied  and  guaranteed 
by  the  manufacturers,  the  Barrett  Manufacturing  Com- 
pany, of  17  Battery  Place,  New  York  City.  It  is  also 
used  in  England  where  it  is  specified  for  the  "Glad- 
well"  system  (see  page  112). 

In  Great  Britain,  a  similar  place  seems  to  be  filled  by 
"Clare's  Patent  Tar  Compo,"  of  Stanhope  Street,  Liver- 
pool, to  which  was  awarded  the  first  prize  at  the  com- 
petitive tests  described  on  page  70,  at  which  there  were 
entered  twelve  other  preparations.  The  tests  then  were 
not  conclusive  as  to  the  others,  as  the  roads  were  not  as 
dry  as  they  should  have  been.  But  the  judges  were 
satisfied  as  to  the  good  qualities  of  the  one  named,  and 
the  road  treated  with  it  showed  best  results  after  five 
months,  due  in  great  measure  to  its  extreme  fluidity, 
which  gave  considerable  penetration  even  when  applied 
cold  as  advised  by  its  makers.  It  also  had  body 
enough  to  hold  together  the  small  dust-forming  par- 
ticles. The  odor  was  unobjectionable.  One-seventh 

73 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

gallon  per  square  yard  was  applied  in  two  coats,  costing 
for  the  material  a  little  over  one  cent  per  square  yard. 


CONDITIONS. 


The  same  conditions  of  season,  climate,  and  road 
apply  to  both  of  these  materials,  except  that  in  England 
and  France  the  cost  of  application  is  less  and  the  rapidity 


PRELIMINARY  SWEEPING  IN  PREPARATION  FOR  TARVIA  (Jackson,  Term.). 

is  greater,  because  of  the  improved  pneumatic  machines 
there  used  for  spreading. 


TARVIA. 


Preparations. — A  road  to  be  treated  with  this,  or 
with  any  tar,  should  be  of  well-built,  firmly  bonded 
broken-stone  in  fairly  smooth  condition.  If  it  is  newly 


74 


COAL-TAR  PREPARATIONS. 


SPREADING  BY  HOSE  FROM  TANK.     (Michigan  Boulevard,  Chicago). 


THE  FINAL  ROLLING.    (Pittsburg,  Pa.). 
TARVIATING. 

75 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

built  it  should  have  been  opened  to  traffic  and  thor- 
oughly dried  out  before  preparing  to  tar  it.  Then  the 
surface  should  be  swept  or  scraped  until  the  fragments 
forming  the  wearing  surface  are  exposed. 

If  it  is  an  old  road,  such  thorough  cleaning  is  specially 
important  in  order  to  remove  any  caked  screenings  which 
may  have  been  left  on  the  surface  to  protect  it,  or  any 
foreign  matters  which  may  be  there.  If  not  removed 
before  the  tarvia  is  spread,  they  will  afterward  dry  out 
and  become  loose  and  break  the  tarviated  surface. 


HOT   TARVIA   TREATMENT. 

When  the  firmly-bonded  macadam  is  thoroughly 
cleaned  and  perfectly  dry,  close  the  road  to  all  traffic, 
or  if  this  is  not  possible,  close  half  of  its  width. 
Select  a  warm,  dry  day  in  summer,  heat  the  tarvia 
(designated  as  "tarvia  A"  and  having  specific  gravity 
of  1.30)  to  160°  or  180°  F.,  and  evenly  spread  one- 
third  to  one-half  gallon  per  square  yard.  To  heat  it, 
use  kettles  with  furnace  beneath,  mounted  on  wheels, 
or  a  tank-wagon  fitted  with  fire-box;  or  a  tank  con- 
taining steam-coils  heated  from  a  boiler;  or,  in  some 
cases,  the  tarvia  is  brought  hot  in  tanks  from  the 
factory  (see  pages  63  and  120  ). 

Spreading. — To  distribute  it  evenly  over  the  road,  if 
none  of  the  tar-spraying  machines  described  on  page 
62  are  available,  or  if  there  is  no  specially  arranged 
sprinkling-cart  or  " White"  sprinkler,  then  the  spread- 
ing can  best  be  done  with  an  open  hose  from  a  tank- 
wagon,  or  from  the  bottom  of  a  wheeled  kettle,  or  by 
hand  with  pails.  In  either  case,  allowing  it  to  flow 

76 


COAL-TAR  PREPARATIONS. 

onto  the  road  and  there  having  four  men  spreading  the 
tarvia  with  street-sweeper's  fibre  brooms. 

Covering. — Traffic  should  be  shut  off  from  the  tarred 
surface  for  two  hours  or  more,  until  the  tarvia  has 
been  practically  absorbed,  when  new  stone  screenings 
should  be  spread  to  take  up  any  surplus  of  tar  which 
may  remain  on  the  surface,  and  the  top  should  then  be 
finished  by  rolling.  After  a  few  days,  the  road  should 
be  swept  to  remove  any  loose  particles  not  bonded. 

Cost. — The  grade  of  tarvia  thus  used  is  "heavy," 
having  specific  gravity  of  1.30,  and  being  known  as 
"tarvia  A."  This  may  cost  $500  to  $700  per  mile  of 
sixteen-feet  roadway,  varying  with  the  cost  of  screenings 
and  with  the  freight-rate  on  tarvia. 

COLD    TARVIA    TREATMENT. 

This  grade  of  tarvia  is  " lighter"  than  "A,"  having 
a  specific  gravity  of  1.10,  and  it  is  designed  for  use  at 
less  cost  (about  half  that  of  "A"),  without  heating, 
and  also  without  need  for  covering  with  screenings. 

Spreading. — Any  unskilled  workman  can  apply  it 
with  a  hand-watering  pot  to  a  dry,  hard,  broken-stone 
roadway,  after  sweeping  the  surface  clean  with  a  com- 
mon broom.  This  grade  of  tarvia  was  first  used  in 
September,  1907,  on  the  Merrick  road  between  Bellmore 
and  Wantagh,  and  at  Oyster  Bay,  and  at  Hyde  Park, 
all  on  Long  Island  near  New  York.  The  resulting 
surfaces  are  shown  in  views  on  page  79,  where  the 
fragments  of  stone  forming  the  mosaic-like  surface  can 
be  plainly  seen  but  are  firmly  held  in  a  matrix  of  tar 
and  dust.  These  roads  are  macadam  which  had  been 
stripped  of  the  protective  layer  of  screenings  by  the 

77 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

passage  of  many  motor-cars  at  excessively  high  speed, 
so  that  the  one  and  one-half  inch  fragments  of  stone 
were  exposed;  prompt  treatment  was  needed  to  save  it. 
The  "B"  tarvia  was  put,  cold,  into  the  tank  of  an 
ordinary  watering-cart  to  which  was  fitted  a  special 
sprinkler,  consisting  of  a  one  and  one-half  inch  pipe, 
perforated  with  eight  one-eighth  inch  holes  distributed 
over  each  inch  of  length.  The  road-surface  was  first 
swrept  clean  and  was  then  sprinkled  with  one-third 
gallon  per  square  yard,  which  was  then  allowed  to 
spread  and  be  absorbed.  No  brooms  were  used  on 
the  tarvia,  which  was  at  once  covered  with  the  sweep- 
ings from  the  adjoining  roadside.  Traffic  was  not 
interrupted  during  or  after  the  application. 

Results. — There  were  no  objectionable  features;  it 
did  not  track,  nor  was  it  picked  up  by  motor-car  tires; 
it  gradually  cemented  the  binder  in  the  road-surface  to 
resemble  asphalt,  so  that  the  road  could  be  cleaned, 
and  the  binder  dust  was  no  longer  sucked  out  by  the 
rubber  tires  of  passing  motor-cars. 

Cost. — One  treatment  is  intended  to  prevent  dust 
and  to  reduce  wear  for  a  year  at  an  average  cost  of 
three  cents  per  square  yard,  or  $300  per  mile  of 
sixteen-feet  roadway. 

MASSACHUSETTS   ROADS. 

On  the  main  roads  radiating  from  Boston,  macadam 
of  the  best  character  has  been  built  and  maintained  by 
the  Massachusetts  Highway  Commission,  and  has  been 
subjected  to  exceptionally  heavy  and  fast  motor-car 
traffic,  as  well  as  to  the  traffic  of  many  horse-drawn 
vehicles.  Franklin  C.  Pillsbury,  division  engineer  of 

78 


EAST  MAIN  STREET,  OYSTER  BAY,  L.  I.,  N.  Y. 


MERRICK  ROAD,  BETWEEN  BELLMORE  AND  WANTAGH,  L.  L,  N.  Y. 
COLD  APPLICATIONS  OF  TARVIA  "B." 

79 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

the  Commission,  states  that  the  motor-car  traffic  was 
so  injurious  during  1906  and  1907  that,  if  newly  built, 
the  roads  would  need  resurfacing  in  two  years,  and 
that  if  not  preserved  by  some  new  method  little  would 
be  left  of  some  of  these  macadam  roads  in  1908. 


TARVIA   ON   PARK   ROADS. 

Roads  maintained  by  the  Massachusetts  Metropolitan 
Park  Commission  are  described  by  John  R.  Rablin, 
engineer  of  the  Park  Commission.  Three  and  one-half 
miles  of  park  roadways  were  tarviated  in  1906,  using 
hot  tarvia  "A,"  covered  with  screenings.  After  a  year 
of  use,  including  the  severe  winter  of  1906-7,  about  half 
of  this  was  re-treated  during  July  and  August,  1907. 
From  about  one-ninth  of. the  whole,  the  surface  layer  of 
tar  and  screenings  scaled  off  in  pieces  one-quarter  inch 
thick  when  the  frost  came  out  in  the  spring  of  1907, 
evidently  as  a  direct  result  of  an  excess  of  screenings 
which  was  left  on  the  road  when  the  tarvia  was  applied 
and  which  prevented  the  tarvia  from  penetrating  at  the 
spots  so  covered.  In  general,  the  winter  had  no  bad 
effect  on  the  parts  properly  treated. 

Cost. — The  average  cost  of  the  1906  treatment,  using 
tarvia  "A"  hot,  and  including  screenings,  was  about 
six  and  four- tenths  cents  per  square  yard,  and  the 
re-treatment  in  1907  cost  about  the  same.  Meantime 
the  roadways  were  free  from  mud  and  dust.  During 
1907  other  park  roadways  in  the  same  system, 
equivalent  in  all  to  ten  miles  of  sixteen-feet  road,  were 
treated  with  tarvia  "A"  at  costs  ranging  from  five  and 
eight-tenths  cents  to  nine  and  three-tenths  cents  per 

80 


COAL-TAR  PREPARATION. 

square  yard,  varying  with  the  condition  of  the  roads, 
necessitating  more  or  less  labor,  the  cost  of  which 
ranged  from  one  cent  to  three  cents  per  square  yard. 
The  cost  of  the  tarvia  varied  with  the  quantity,  from 
two  and  one-half  cents  to  three  and  eight-tenths 
cents  per  square  yard,  depending  also  upon  the 
road  condition. 

DEFECTS. 

On  some  portions  of  these  roads  the  tarvia  and  screen- 
ings gathered  in  bunches  by  a  peculiar  and  unexplained 
action;  this  did  not  injure  the  effectiveness  but  was 
unsightly.  This  same  bunching  has  been  observed  else- 
where and  has  not  been  traced  to  faults  in  the  road- 
surface,  which  was  in  each  case  put  in  perfect  order 
before  beginning  the  tarvia  treatment.  The  bunches 
gradually  wear  off  and  leave  no  break. 


LYNN,    MASS. 

One  of  the  most  marked  instances  of  the  good  results 
from  tarviating  a  road  has  been  at  Lynn,  Mass.,  where 
the  Massachusetts  Highway  Commission  built,  in  1906,  a 
mile  of  good  macadam  across  the  marshes,  where  it  was 
fully  exposed  to  sun  and  wind,  and  had  as  much  high- 
speed motor-car  traffic  as  any  road  in  Massachusetts. 
As  the  result  of  these  conditions  the  road  had  to  be 
re-surfaced  in  one  year  after  completion. 

Removal  of  Crust. — One  month  later,  in  July,  1907, 
tarvia  "A"  was  applied,  after  first  removing  a  half-inch 
crust  of  screenings  which  had  been  wet  with  salt  water 
and  had  become  so  hard  that  harrows  and  picks  were 

81 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

used  to  loosen  it  at  considerable  cost.  Where  small 
patches  of  this  crust  were  inadvertently  left,  it  was  after- 
wards necessary  to  remove  them  also. 

Methods. — The  tarvia  was  brought,  still  hot,  from  the 
works  in  Lynn,  where  it  was  prepared;  but  it  proved 
that  the  best  surface  was  made  where  the  coolest  tarvia 
was  used.  The  location  made  it  necessary  to  permit 
travel  during  tarviating,  and  half  of  the  width  was 
therefore  treated  at  a  time,  with  the  result  that  the 
lapping  of  the  two  coats  shows  at  the  center  and  is 
unsightly. 

Cost  and  Results. — The  average  cost  was  about  eight 
cents  per  square  yard,  including  the  covering  of  the 
tar  with  coarse,  quarter-inch  sand,  which  was  found 
to  be  more  effective  than  fine  sand.  As  the  result  of 
tarviating  this  road,  it  was  free  from  dust  and  showed 
practically  no  signs  of  wear  from  the  passage  of  many 
high-speed  motor-cars  during  the  next  four  months  of 
1907. 

WAYLAND,    MASS. 

New  Surface. — At  Wayland,  Mass.,  in  1906,  a  new 
broken-stone  surface  was  put  upon  parts  of  an  old 
macadam  road.  It  has  usually  been  considered  that  a 
new  surface  should  be  used  for  at  least  a  month  before 
treatment  with  prepared  tar;  but  in  this,  case  the  clean 
newly-rolled  stone  was  at  once  tarviated  without  any 
preliminary  spreading  of  the  usual  screenings  and 
water.  The  results  of  the  tarring  were  best  on  the 
newly  surfaced  parts.  For  the  material  to  cover  the 
tarvia,  various  grades  of  sand  and  of  stone  screenings 
were  tried,  and  the  best  was  found  to  be  the  one- 

82 


COAL-TAR   PREPARATIONS. 


quarter  inch,  or  "pea,"  stone  from  which  all  free  dust 
had  been  removed. 


NEWTON,    MASS. 

Charles  W.  Ross,  widely  known  as  one  of  the  most 
experienced  road-builders  in  the  United  States,  formerly 
State  Highway  Commissioner  of  Massachusetts,  who 
has  built  and  maintains  the  model  road  system  of  the 
Newtons,  used  tarvia  "A"  in  1906  and  1907  on  the 
fine  macadam  roadways  in  Newton,  Mass.,  adjoining 
Boston,  where  the  high-speed  motor-car  traffic  is  excessive 
and  destructive,  especially  on  Commonwealth  Avenue, 
which  extends  from  Boston  through  Newton. 

Methods. — In  July,  1906,  where  the  motor-cars  had 
completely  taken  off  the  binding  material  and  had 
left  the  one-inch  stones  bare  and  beginning  to  ravel, 
he  swept  the  surface  as  clean  as  possible  with  a 
street-sweeping  machine,  and  then  spread  about  one- 
half  gallon  of  hot  tarvia  per  square  yard,  covering  it 
at  once  with  a  thin  layer  of  one-quarter  inch  sand  or 
fine,  screened  gravel  (avoiding  the  dust  of  screenings) 
and  then  rolled  it.  This  formed  a  tarviated  surface 
which  stood  well  through  1906,  and  improved  during 
1907,  when  more  similar  work  was  done  on  adjoining 
roads. 

Cost. — The  itemized  cost  of  the  work  was: 

Tarvia  "A, "  at  8  cents  per  gallon 3T^  ct.  per  sq.  yd. 

Screening,  or  coarse  sand T77      "  " 

Labor,  cleaning,  spreading,  etc 4T3^      "  " 

Teaming,  hauling  tarvia,  sand,  etc i^      ' c  " 

Rolling T6Q-      "  " 

Total n^      "  " 

83 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

On  roadways  having  very  heavy  teaming,  Mr.  Ross 
has  swept  and  spiked  the  surface,  covered  it  with  a 
layer  of  one-inch  stone,  rolled  it  smooth,  applied  one 
and  one-half  gallons  of  hot  tarvia  "A"  per  square  yard, 
covered  this  with  screened  gravel  and  rolled  again  till 
hard.  All  this  cost  nineteen  cents  per  square  yard,  but 
Mr.  Ross  believes  that  it  will  last  four  or  five  years,  and 
that  it  is  well  worth  the  extra  material  used. 

PENETRATION. 

In  all  these  applications  of  tarvia  in  the  vicinity  of 
Boston,  the  material  was  of  grade  "A,"  specific  gravity 
about  1.30,  and  it  was  all  heated  to  170°  to  180°  F. 
or  more,  to  facilitate  spreading  by  brooms.  The  heat- 
ing aids  distribution,  but  has  little  or  no  effect  upon 
penetration,  which  varies  on  these  roads,  which  are 
exceptionally  good,  from  one-half  inch  on  very  hard, 
smooth  surface  to  three-quarters  of  an  inch  or  more 
in  some  cases. 

RHODE   ISLAND   ROADS. 

In  the  State  of  Rhode  Island  during  1906  and  1907, 
the  State  Board  of  Public  Roads  tarviated  several  State 
roads,  and  among  them  was  one  in  the  town  of  Tiverton, 
R.  I.  The  operations  are  described  by  Asst.  Engr. 
Arthur  W.  Blanchard,  Assoc.  Prof,  of  Civ.  Engineering 
in  Brown  University. 

Methods. — The  road  was  swept  in  the  usual  way 
with  stiff  brooms  until  the  mosaic  surface  of  the  No. 
2,  or  top  course,  was  exposed,  when  hot  tarvia  "A" 
was  poured  upon  it  and  spread  by  brushes,  and  a  thin 
coat  of  fine  sand  was  then  spread  over  the  tarvia. 

84 


COAL-TAR   PREPARATIONS. 

Steep  Grade. — The  section  thus  treated  was  on  a 
grade  of  seven  and  one-quarter  per  cent,  and  the 
action  on  this  steep  grade  was  specially  noted.  The 
tarviated  surface  proved  effective  in  shedding  the 
water  into  the  gutters,  preventing  the  road  from  being 
gullied,  while,  contrary  to  the  experience  of  English 
engineers  with  steep  gradients,  there  was  no  trouble  or 
complaint  as  to  slipping. 

Results. — The  road  was  subject  to  more  than  the 
average  motor-car  traffic,  being  part  of  the  interstate 
trunk  line  leading  to  Newport;  but  the  surface  had 
not  scaled  nor  worn  down  to  the  stone  after  a  season 
of  use,  and  it  was  free  from  dust.  The  cost  was  eight 
cents  per  square  yard. 

On  other  roads  similarly  treated  the  tarvia  coating 
scaled  off  in  spots  and  on  the  edges,  but  as  a  whole  the 
work  proved  to  be  satisfactory. 

UNITED    STATES    EXPERIMENTS. 

The  United  States  Office  of  Public  Roads,  Logan 
Waller  Page,  director,  during  1907  conducted  experi- 
mental work  of  surface  treatments  at  Wayland,  Mass., 
in  co-operation  with  the  Massachusetts  Highway  Com- 
mission. Crude  coal-tar  was  used  alone  and  in  special 
preparations  and  in  various  combinations  with  water- 
gas  tar,  of  each  of  which  the  composition  was  as  follows 
(see  also  page  59): 


85 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


TABLE. 
SPECIFIC  GRAVITY  AND  COMPOSITION  OF  TAR  PRODUCTS. 


Kind  of  tar. 

Specific 
gravity. 

Ammonical 
water. 

Total  light 
oils  to 
120°  C.  (or 

338°  F.). 

Total  dead 
oils,  i7o°C. 
to  270°  C. 
(or  to 

518°  F.). 

Residue 
per  cent  by 
difference. 

Water-gas  tar  

I   041 

2   4% 

21  6%l 

*2    0%2 

2d    0%3 

Coal-tar 

I     2IO 

2    0% 

17    3%4 

26  o%5 

CA    8C/6 

Special  tar  preparation. 

I.I77 

0.0% 

12.  8%2 

47-6%7 

39-6%6 

1.  Distillate  mostly  liquid. 

2.  Distillate  all  liquid. 

3.  Pitch  very  brittle. 

4.  Distillate  mostly  solid. 


5.  Distillate  one-half  solid. 

6.  Pitch  hard  and  brittle. 

7.  Distillate  one-third  solid. 


Methods. — The  roads  treated  were  mixed  trap  and 
granite  macadam  about  ten  years  old,  being  parts 
of  the  main  thoroughfare  between  New  York  and 
Boston,  sixteen  miles  from  the  center  of  Boston, 
having  heavy  traffic  of  both  motor-cars  and  teams, 
producing  excessive  dust.  The  applications  were  made 
during  the  month  of  August,  1907,  only  in  dry  and 
warm  weather,  and  were  surface  treatments  only. 
The  general  method  was  to  sweep  from  the  road 
all  loose  dust  and  detritus  just  before  the  application 
of  the  tar.  This  was  applied  hot  or  cold,  as  stated, 
from  a  hose  connected  to  a  wheeled  kettle  or  tank- 
wagon,  four  laborers  following  with  stiff,  long-handled 
brooms  to  spread  the  tar  and  to  work  it  into  the  sur- 
face. As  the  roads  could  not  be  closed  to  traffic,  a  light 
covering  of  gravel  or  screenings  was  applied  at  once, 
though  better  results  would  have  been  produced  if 
the  tar  could  have  been  allowed  to  lie  for  several 
hours  before  covering  it.  Finally,  fine  gravel  or  half- 

86 


COAL-TAR  PREPARATIONS. 

inch  clean  trap  screenings  was  spread  as  a  covering 
material  in  sufficient  quantity  to  take  up  all  excess  of 
tar  and  to  produce  an  even  surface,  when  the  whole 
was  rolled  with  a  twelve-ton  roller  until  firm  and 
smooth.  The  costs  varied  from  nine  cents  to  thirteen 
cents  per  square  yard,  but  these  are  stated  to  be  high 
because  of  the  small  areas  treated  and  the  excessive 
repairs  and  renewals  required  in  preparation,, 

Conclusions. — The  general  conclusion  here  seemed  to 
be  as  elsewhere  that  coal-tar  in  some  form  was  preferable 
to  water-gas  tar  in  any  form,  being  more  effective  as  a 
binder  and  more  durable.  The  crude  coal-tar  showed 
very  favorably  in  comparison  with  the  more  costly  special 
preparation  of  coal-tar.  This  initial  saving  was  some- 
what offset  by  the  fact  that  the  crude  coal-tar  required 
heating  to  a  temperature  of  at  least  145°  F.,  ranging  up 
to  195°  F.,  while  the  prepared  coal-tars  could  be  used 
cold.  The  slippery  surface  during  frosty  weather  was 
an  objection  which  was  common  to  all  the  coal-tars. 

The  experiments  led  to  the  conclusion,  as  expressed 
by  Director  Page,  that  the  surface  treatments  with  tar 
as  above  described,  are  palliatives  rather  than  preventives 
of  dust,  and  that  some  more  permanent  method  of  using 
coal-tar  is  essential  for  satisfactory  results  (see  page  116). 

APPLIANCES. 

Crude  methods  were  used  in  all  these  operations, 
although  the  engineers  in  charge  appreciated  the  desir- 
ability of  the  improved  appliances  used  in  France  and 
in  England  for  similar  works  (see  pages  70  and  89). 

Heating. — The  Boston  outfit  consisted  of  two  five- 
barrel  heating  kettles  mounted  on  wheels,  one  pair  of 

87 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

horses  to  move  them,  twelve  to  fourteen  laborers  to 
sweep  the  surface  and  to  spread  and  cover  the  tarvia, 
and  teams  to  haul  sand  and  screenings  as  needed. 
The  Rhode  Island  outfits  were  similar.  The  hot  tarvia 
was  led  from  the  bottom  of  each  kettle  through  a  pipe, 
valve,  and  hose,  from  the  open  end  of  which  latter  it 
flowed  by  gravity  out  upon  the  road-surface  where 
hand-brooms  were  used  to  spread  it.  No  attempts 
could  be  made  to  spray  the  tar,  nor  to  force  it  into 
the  road,  nor  to  get  uniformity  and  rapidity  of  flow 
by  pneumatic  pressure.  Under  these  restricted  condi- 
tions, 1200  feet  of  sixteen-feet  roadway,  or  2000  square 
yards  of  surface,  was  an  average  day's  work,  or  less 
than  one-twentieth  of  the  rate  of  work  of  the  best 
machines  in  England  and  France,  where  much  better 
penetration  is  also  secured. 

THE  " WHITE"  MACHINE. 

Spreading— -The  " White"  machine,  made  by  Theo- 
dore F.  White  of  Los  Angeles,  California,  and  gener- 
ally used  in  forming  the  petrolithic  roads  of  that 
region,  has  also  been  used  on  some  of  the  New  York 
and  Massachusetts  oiled  roads.  It  is  a  patented 
attachment  to  the  rear  of  an  ordinary  sprinkling-tank 
by  which  the  gravity  flow  of  the  contents  of  the  tank, 
usually  heated  crude  asphaltic  oil,  is  controlled  and 
regulated  in  width  of  application  varied  from  eighteen 
inches  to  six  feet,  by  gauges  and  valves,  so  that  two 
men  with  four  horses  treat  half  a  mile  of  sixteen-feet 
road  per  day.  This  machine  would  seem  to  be  well 
adapted  to  applying  heated  tarvia  "A,"  or  cold  tarvia 
"B,"  or  any  thin  tar  preparation. 


TAR-SPRAYING  MACHINES. 


AITKEN'S. 

The  best  of  the  tar-spraying  machines  (page  70)  is 
the  "Aitkens'  patent  pneumatic  tar-spraying  apparatus," 
made  by  Thos.  Aitken,  M.  Inst.  C.  E.,  Cupar,  Fife, 
Scotland,  by  which  coal-tar,  cold,  can  be  sprayed  in 
varying  quantities  as  desired,  under  sustained  pneumatic 
pressure  sufficient  to  cause  penetration  to  depth  of  one 
to  three  inches  into  the  hard  surface  of  a  used  macadam 
road.  It  can  be  fitted  on  an  ordinary  watering-cart, 
using  the  tank  to  carry  the  supply  of  tar,  and  attaching 
to  the  cart-frame  the  compressed-air  "receiver"  and  the 
pump,  valves,  sprayers,  and  devices,  all  actuated  by 
power  from  the  wheel-axle  of  the  horse-drawn  cart. 
A  large  sized  machine  is  motor-driven. 

Attached  back  of  the  tank  is  the  " receiver,"  which  is 
a  steel  cylinder  into  which  is  first  forced  air  at  100  pounds 
to  150  pounds  pressure  per  square  inch  by  means  of 
the  same  force  pump  which  also  draws  the  tar-supply 
from  the  tank.  When  this  air  pressure  is  reached,  as 
shown  by  a  gauge,  the  pump  is  connected  to  the  tank, 
and  the  receiver  is  then  half  filled  with  tar,  causing 
the  pressure  in  the  receiver  to  rise  to  200  pounds  to  250 
pounds  per  square  inch,  when  the  machine  is  ready  for 
operation,  for  which  only  two  men  are  required.  The 

89 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

outlet-valve  is  then  set  to  give  a  fine  spray,  or  a  coarser 
one,  as  desired,  thus  varying  the  quantity  of  tar  used 
from  about  one-ninth  gallon  to  about  one-fifth  gallon 
per  square  yard  of  the  surface  being  treated.  The  supply- 
valve  from  the  tank  being  meanwhile  regulated  to  equal 
the  outlet  and  to  thus  maintain  the  uniform  pressure  in 
the  "receiver." 

The  method  of  using  this  machine  to  tar  roads  is 
described  in  the  1907  edition  of  Aitken's  "  Road-making 
and  Maintenance,"  in  effect  as  follows,  the  author  and 
inventor  being  a  recognized  English  authority  on  road- 
construction  : 

SPRAYING   NEW    TAR-MACADAM. 

When  a  new  macadam  road  is  to  be  treated  with  tar, 
the  perfectly  dry  broken  stone,  after  being  spread  over 
the  dry,  properly  drained,  formed,  and  rolled  roadbed, 
is  not  rolled  until  the  tar-sprayer  has  passed  twice  over 
the  loose  dry  stones,  when  the  spray  of  tar,  forced 
through  the  fine  spraying-nipples,  penetrates  the  loose 
mass  of  stone  to  a  depth  of  three  to  five  inches,  with  the 
effect  of  covering  all  the  surfaces  of  all  the  dry  fragments 
with  a  film  of  tar,  which  is  thus  equally  diffused.  If 
the  stone  fragments  are  two  inches  to  two  and  one-quarter 
inches  size,  the  course  is  then  covered  with  a  layer  of 
stone  chips,  or  one-half  inch  screenings.*  If  the  stone 
fragments  are  three-quarter  inch  to  one  inch  size,  the 
layer  of  stone  chips  is  not  needed. 

Rolling. — The  main  point  is  to  fill  the  voids  in  order 
to  secure  binding  with  as  little  tar  as  possible,  and  to 

*  The  writer  considers  it  better  practice  to  defer  this  covering  of  stone-chips 
or  screenings  until  after  the  base-course  has  been  rolled  and  consolidated. 

90 


TAR-SPRAYING  MACHINES. 

roll  thoroughly  as  soon  as  thirty  to  fifty  yards  in  length 
of  the  full  width  of  the  road  is  sprayed  and  covered 
as  described;  it  being  necessary  to  complete  a  section 
the  same  day  that  it  is  begun  in  order  to  avoid  chance 
of  rain.  After  the  rolling  has  brought  the  tarred  stones 
to  a  firm  surface,  it  is  again  sprayed  once,  and  then 
covered  with  a  one-quarter  inch  layer  of  screenings 
and  again  rolled  to  a  finished  condition.  The  quan- 
tity of  tar  thus  used  varies  with  the  character  and 
size  of  the  stone  from  four  gallons  to  six  gallons  per 
ton  of  stone,  or  an  average  of  five  gallons  per  ton, 
which  equals  about  six  gallons  per  loose  cubic  yard. 

Cost  in  England. — This  rate  for  a  two  and  one-third 
inches  finished  thickness  of  rolled  three-quarter  inch 
to  one  inch  stones  (three  and  one  half  inches  loose) 
would  average  about  six-tenths  gallon  per  square  yard 
of  surface.  A  fair  day's  work  for  an  engineman  and 
tar-sprayer,  three  men  and  two  horses,  using  625  gal- 
lons of  tar  at  four  cents  per  gallon,  would  be  to  spray, 
roll,  and  cover  as  described  125  tons,  or  102  loose 
cubic  yards,  of  stone  at  a  cost  (in  England)  of  twenty- 
eight  cents  per  ton  or  thirty-three  cents  per  loose  cubic 
yard,  making  712  square  yards  of  a  two  and  one  third 
inches  finished  surface,  or  400  lineal  feet  of  sixteen-feet 
roadway  per  day  of  ten  hours.  This,  in  England  with 
wages  at  ten  cents  per  hour  and  tar  at  four  cents  per 
gallon,  would  equal  a  cost  of  four  and  one-half  cents 
per  square  yard,  or  three  cents  more  than  working  with 
water  only.  This  equals  $281  per  mile  of  sixteen-feet 
roadway. 

Cost  in  United  States. — In  the  United  States,  with 
wages  at  twenty  cents  per  hour  and  tar  at  five  cents 
per  gallon,  this  would  equal  an  added  cost,  for  tarring 

91 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

a  two  and  one-third  inches  finished  surface  layer,  of 
five  and  one-half  cents  per  square  yard,  or  $516  per 
mile  of  sixteen-feet  roadway.  The  reduced  cost  of 
maintenance  and  of  cleaning  is  expected  to  offset  this 
greater  cost  of  construction. 

Result. — The  macadam  road  thus  built  with  good 
tar  is  dustless  and  is  better  and  more  permanent  than 
the  ordinary  broken-stone  roads  built  with  water,  pro- 
vided that  care  is  taken,  so  far  as  possible,  to  con- 
solidate the  stones  by  rolling  so  that  the  fragments 
bond  each  other  and  do  not  depend  upon  the  tar  for 
support.* 

SPRAYING    SURFACE    OF    OLD    MACADAM. 

For  tar-spraying  the  surface  of  an  old  broken-stone 
road,  the  surface  must  be  clean  and  perfectly  dry,  taking 
special  care  to  look  for  and  to  correct  slight  depressions 
in  shaded  parts  of  the  road  where  moisture  is  likely  to 
linger  even  when  the  rest  of  the  road  is  perfectly  dry. 
The  tar-spray  is  applied  to  one-half  of  the  width  of  the 
roadway,  turning  traffic  onto  the  other  half  for  twenty- 
four  hours.  This  has  been  done  to  half  of  a  sixteen-feet 
road,  by  an  Aitken  tar-sprayer,  at  the  rate  of  two-thirds 
of  a  mile  per  hour. 

Cost. — The  cost  of  cleaning  the  road  and  spraying 
the  tar  (when  a  horse-drawn  apparatus  is  used)  has 
been  about  one-half  cent  per  square  yard  for  labor, 
or  $47  per  mile  of  sixteen-feet  roadway.  Using  one- 
eighth  gallon  of  tar  per  square  yard  with  tar  at  five 

*  This  feature  is  brought  to  its  perfection  in  the  graduated  and  adjusted 
sizes  used  in  bitulithic  or  quarrite  roads;  but  such  accuracy  in  filling  voids  is 
not  practicable  in  ordinary  work. 

92 


TAR-SPRAYING   MACHINES. 

cents  per  gallon,  the  total  cost  for  one  application,  in- 
cluding labor  as  stated,  would  be  one  and  one-eighth 
cents  per  square  yard,  or  $111  per  mile  of  sixteen-feet 
roadway.  With  the  tar-sprayer  attached  to  a  motor- 
driven  van  carrying  800  gallons  of  tar,  greater  lengths 
of  road  can  be  treated  per  day,  and  the  cost  of  spray- 
ing is  proportionately  less.  This  does  not  include  the 
cost  of  dusting  or  sanding  the  surface  to  cover  the 
fresh  tar,  but  such  sanding  would  usually  be  required 
in  any  case  on  any  ordinary  macadam  road.  Neither 
does  it  include  any  allowance  for  the  probable  loss, 
delay,  and  damage  likely  to  be  caused  by  rains  which 
may  come  upon  the  tarring  work  while  it  is  unfinished. 

TARSPRA. 

The  "Tarspra,"  of  No.  20  Victoria  Street,  London,  S.W., 
is  another  patented  tar-spraying  machine  which  is  used 
in  a  similar  way  and  with  about  the  same  results  as 
the  one  just  described.  The  "Tarspra"  is  made  in 
three  sizes  of  200  gallons,  700  gallons,  or  1000  gallons 
capacity  each,  and  these  are  horse-drawn  or  motor- 
driven.  This  apparatus  takes  the  tar,  either  cold  or  hot, 
by  means  of  a  double-acting  force  pump  fixed  at  one 
side  of  the  tar-tank  and  actuated  by  chain-gear  from  the 
wheel-axle.  This  pump  forces  the  tar  to  atomizing 
nozzles  at  the  rear,  where  it  is  discharged  in  a  fine  spray 
and  distributed  in  an  even  coating  under  pressure  of 
200  pounds  per  square  inch,  the  jets  being  so  disposed 
as  to  impinge  upon  each  other  in  such  way  as  to  atomize 
the  spray,  giving  two  inches  of  penetration.  Thirty  or 
more  of  these  machines  of  different  sizes  worked  during 
1907  in  various  parts  of  England,  more  particularly  in 

93 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

the  County  of  Kent,  tarring  roads  in  some  cases  at  the 
rate  of  a  mile  per  hour.  Various  improvements  suggested 
by  practical  experience  will  be  embodied  in  future 
machines. 


LASSAILLY- JOHNSTON. 

The  "Lassailly- Johnston  Patent  Tar  Road-binder," 
after  having  been  successfully  used  on  the  roads  in 
France  for  several  years,  was  introduced  into  England 
in  1906  in  an  improved  form  as  a  competitor  with 
the  two  pneumatic  machines  just  described.  It  dis- 
tributes hot  tar  by  gravity  flow,  depending  upon  auto- 
matic brushes  and  absorption,  instead  of  forcing  a 
fine  spray  as  is  done  by  the  English  machines.  It  is 
more  complicated  than  they  are,  consisting  of  two 
vehicles,  one  in  which  to  cook  or  heat  the  tar  to 
200°  F.  by  means  of  steam-coils,  and  the  other  with 
which  to  distribute  it.  Into  the  heater  the  cold  tar 
is  drawn  by  a  steam-created  vacuum,  and  from  the 
heater  the  hot  tar  is  forced  quickly  into  the  main  tank 
of  the  spreader,  which  is  drawn  by  horses.  From  this 
main  tank  its  flow  into  the  regulating-tank  is  controlled 
by  a  float-valve  which  maintains  a  constant  level,  so  that 
the  gravity  flow  through  nozzles  is  uniform  onto  the  road, 
where  four  automatic  weighted  brushes  spread  it  in  an 
even  and  smooth  layer,  one  laborer  following  with  a 
hand-broom  to  insure  complete  spreading.  The  hot  tar 
is  said  to  penetrate  one  to  three  inches  into  the  road- 
surface.  It  puts  on  a  neavier  coating  than  the  spraying- 
machines  and  one  which  is  more  enduring,  but  the 
apparatus  with  its  need  for  heating  is  more  cumber- 
some and  slow  to  handle.  It  has,  however,  done  a  vast 

94 


TAR-SPRAYING  MACHINES. 

amount  of  good  work  both  in  France  and  England. 
One  of  these  outfits  has  covered  2500  square  yards  (or 
over  one-half  mile  of  half  the  width  of  a  sixteen-feet 
roadway)  per  hour,  using  on  it  five  tons  of  boiling  tar, 
thus  doing  the  work  better  than  was  formerly  done  in 
France  by  fifty  men. 

Cost.— The  cost,  where  tar  is  bought  at  five  cents 
per  gallon,  is  stated  to  be  about  six  cents  per  square 
yard  for  two  complete  coatings,  including  a  covering 
over  the  fresh  tar  of  stone  chips,  trass,  and  dry  Port- 
land cement. 

GOOD    RESULTS. 

The  effect  under  ordinary  conditions  is  to  make  the 
road  free  from  mud  and  dust  for  a  year. 

In  France. — The  resultant  annual  saving  in  the  re- 
duced cost  of  sweeping,  mud-scraping,  and  repairs,  is 
stated  by  M.  Heude,  chief  'engineer  of  roads  and 
bridges  of  the  department  of  the  Seine  and  Marne, 
to  be  one  cent  per  square  yard.  The  actual  quan- 
tity of  material  swept  from  a  piece  of  thus  tarred 
macadam  road  near  Paris  being  one-twelfth  of  the 
amount  removed  from  the  same  road  during  a  similar 
former  period.  The  same  engineer  states  that  he  tarred 
24,000  square  yards  of  macadam  roads  in  1903,  50,000 
square  yards  in  1904,  150,000  square  yards  in  1905, 
with  good  results  throughout,  the  cost  in  some  cases 
being  less  than  the  savings,  and  that  in  future  all 
newly-made  roads  and  streets  will  be  tarred. 

In  England. — In  England  during  the  five  summer 
months  of  1906,  there  were  thus  tarred  by  the  Lassailly- 
Johnston  machines  about  120  niiles  of  sixteen-feet  roads, 

95 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

including  roads  at  Epsom,  Shoreham,  and  Sutton,  near 
London,  and  at  Hove  and  Worthing,  near  Brighton. 


THWAITE. 

The  "Thwaite  Anti-road-dust"  machine  is  a  steel 
tank  or  boiler,  fitted  with  a  furnace-grate  and  a  sprink- 
ling apparatus.  Tar  and  water  are  pumped  into  the 
boiler  where  the  tar  is  heated  to  300°  F.,  and  steam  is 
also  formed  to  give  pressure  for  forcing  the  hot  tar 
through  fine  perforations  of  the  sprinkler  onto  the  road- 
way. Meantime  sprocket-gears  from  the  wheel-axles 
operate  two  force  pumps,  one  to  force  dehydrated  tar 
into  the  boiler  and  the  other  to  force  air  to  add  to  the 
steam  pressure.  The  result  is  that  the  hot  tar  is  so 
atomized  that  the  jets  are  nearly  invisible  until  they 
touch  the  road-surface  which  they  penetrate  effectively, 
spreading  tar  over  the  surface  in  an  enamel-like  coating. 
The  apparatus  is  horse-drawn  or  motor-driven,  and  is 
made  in  several  sizes,  the  larger  of  which  carries  300 
gallons  of  tar.  There  is  also  an  auxiliary  tank,  or  tar- 
boiler  with  furnace-grate,  to  give  continuity  of  operation. 
This  system  prefers  that,  in  addition  to  the  perfect  dry- 
ness  which  is  required  by  all  tar  applications,  the  road- 
surface  shall  be  first  heated  with  their  hot  roller  to  insure 
its  being  dry  and  hot,  and  that  after  tarring,  the  tar 
shall  be  covered  with  hot  sand. 

Cost. — The  first  cost  of  the  comparatively  simple 
apparatus  is  moderate,  and  less  than  the  others. 
The  work  done  is  good  and  effective,  but  the  cost  of 
operation  as  described  is  evidently  greater  than  that 
of  either  the  Aitken,  the  Tarspra,  or  the  Lassailly 
machines. 

96 


TAR-SPRAYING  MACHINES. 


TARMACISER. 

The  "Tarmaciser"  (of  No.  7  Victoria  Street,  West- 
minster, London)  is  a  35  H.P.  steam-traction  engine  to 
which  are  attached  the  various  mechanical  devices  for 
simultaneously  cleaning  and  loosening  the  road-surface, 
removing  the  dust,  heating  and  distributing  the  tar,  and 
spreading  it  with  automatic  brushes,  after  which  the 
dust  previously  taken  from  the  road  is  ejected  over  the 
fresh  tar  and  is  then  rolled  by  the  steam-heated  wheels 
of  the  machine.  It  is  most  complete  and  complex, 
requiring  skilled  adjustment  and  management  and  does 
not  seem  adapted  to  general  use. 

CONCLUSIONS. 

The  number  and  the  variety  of  these  machines  for 
rapidly  applying  tar  are  indications  of  the  general  re- 
cognition of  the  need  for  means  to  quickly  treat  great 
lengths  of  roads  during  the  short  periods  when  weather 
conditions  are  favorable,  all  authorities  agreeing  that 
tar  should  only  be  applied  when  both  air  and  road  are 
warm  and  dry  (see  " Conditions,"  page  67). 

Their  applicability  to  the  original  construction  of  new 
tarred  roads  (see  page  90),  when  surface  treatment  of 
old  roads  is  not  needed,  is  an  important  economical 
feature. 


97 


TAR-MACADAM. 


SUMMARY. 

This  name  is  applied  to  any  crushed-stone,  or  crushed 
slag  construction  in  which  coal-tar,  or  a  bituminous 
cement,  or  a  material  containing  coal-tar  or  bitumen,  or 
both,  is  used  (instead  of  water)  in  binding  the  filler 
between  the  fragments  of  stone,  or  slag;  the  tar  or 
bitumen  remaining  as  a  fixative  to  hold  in  place  the 
stone  chips,  screenings,  or  sand  forming  the  filler, 
"  binder,"  or  matrix  for  the  fragments,  thus  aiming 
to  better  the  road  (as  compared  with  ordinary,  water- 
built  macadam)  by  excluding  water,  reducing  wear  and 
preventing  dust.  The  term  is  used  in  distinction  from 
the  surface  treatment,  or  "  tar-painting,"  described  in 
the  preceding  pages. 

Tar-macadam  may  consist  of  a  tarred  three-inch  sur- 
face layer  only,  as  described  on  pages  82,  105,  and  107. 
Or  more  usually  of  tarring  all  the  fragments  in  the 
entire  road,  either  before  spreading  as  described  on 
pages  105  and  109,  or  after  spreading  in  place  on  the  road, 
as  described  on  pages  107  and  118;  or  the  "Gladwell" 
system,  as  describedon  page  111;  or  the  most  perfect 
form  in  the  bitulithic  pavement,  as  described  on 
page  127. 

98 


TAR-MACADAM. 


COMPARATIVE   COST. 

Any  good  form  of  the  cheaper  tar-macadams  costs 
about  one-third  more  than  the  ordinary  water-built 
macadam  of  the  same  kind  and  depth  of  stone,  because 
of  the  added  cost  of  the  tar  or  bituminous  cement,  and 
also  because  of  the  necessary  restrictions  as  to  working 
only  in  warm  and  dry  weather,  and  also  the  need  of  re- 
pairing the  injuries  done  by  rain  coming  on  incomplete 
work.  But  these  initial  increased  costs  are  offset,  when 
the  construction  succeeds,  by  longer  life  of  the  road  and 
by  less  expense  for  cleaning,  maintenance,  and  repairs. 

RESULTS. 

When  good,  a  tar-macadam  road  is  practically  dustless 
and  noiseless,  offers  little  tractive  resistance,  and  endures 
the  passage  of  the  rubber  tires  of  high-speed  motor-cars; 
and  as  it  sheds  water,  it  is  not  heaved  nor  disintegrated 
by  frost.  It  has  the  disadvantage,  in  common  with 
other  pavements,  of  being  slippery  when  frosty.  Of  the 
several  modified  forms,  the  cheapest  successful  one  seems 
to  be  the  "Gladwell"  system,  described  on  page  111. 

HISTORY. 

Tar-macadam  roadways  were  first  built  on  the  London 
road  at  Nottingham,  England,  at  a  date  variously  stated 
as  1840  and  1845,  and  at  Sheffield  soon  after.  Other 
similar  roads  have  since  been  built  at  many  times  and 
places  in  England  and  in  France,  and  some  in  the 
United  States  since  1900.  The  earlier  ones  used  crude 
coal-tar,  mixed  by  hand  with  various  kinds  of  stone, 

99 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

and  often  produced  failures  because  of  the  poor  quality 
of  the  crude  tar  (see  pages  68  and  71),  or  because  of 
rain  or  cold  during  construction.  Many  of  the  old 
ones,  however,  are  still  in  satisfactory  use,  as  well  as 
many  new  ones. 

In  recent  years  the  necessity  of  having  properly  refined 
tar  has  become  generally  known  (see  page  71),  and  im- 
proved appliances  for  heating  and  hand-mixing  the  tar 
and  stones  have  been  used  with  much  better  results  than 
formerly  as  to  cost  and  character;  the  mixing  has  been, 
effectively  done  in  some  cases  with  an  ordinary  con- 
crete mixer. 

In  1901  the  Warren  Brothers  Company  of  Boston, 
Mass.,  proportioned,  heated,  and  mixed  the  materials 
mechanically,  as  described  on  page  127;  and  in  1904, 
Brown  and  Clarke  of  Nottingham,  England,  produced 
a  steam-operated  machine  which  mechanically  heats  and 
mixes  stones  and  tar,  as  described  at  page  102,  preparatory 
to  spreading  it,  cold,  upon  the  roads.  Tar-spraying 
machines,  and  tar-spreading  machines  adapted  to  tarring 
the  stone  in  place,  after  it  has  been  spread  on  the  road, 
have  been  devised,  and  have  been  used,  as  described  on 
page  71,  in  both  England  and  in  France  for  the  surface 
tarring  of  roads,  but  these  machines  have  not  as  yet 
been  much  used  for  making  tar-macadam  for  which  they 
are  well  suited,  as  described  on  page  65. 

In  1901  there  was  originated  in  the  United  States,  and 
since  widely  used,  the  bitulithic  pavement,  well  known 
as  being  the  highest  grade  of  combination  of  broken  stone 
and  bituminous  cement,  which  is  described  at  page  127, 
with  details  of  the  1907  type  of  portable  outfit  for  build- 
ing it. 


100 


TAR-MACADAM. 


METHODS. 

Tar-macadam  is  more  used  in  England  than  else- 
where, and  the  methods  of  construction  there  have  been 
radically  improved  since  1905.  In  February,  1906,  at 
a  meeting  of  the  Inst.  of  Civil  Engineers,  H.  G.  Whyatt, 
M.  Inst.  C.  E.,  borough  engineer  of  Grimsby,  who  had 
built  tarred  macadam  roads  during  many  years,  de- 
scribed a  new  equipment  which  he  had  just  finished 
at  Grimsby  (which  was  like  one  built  -  at  Sheffield  in 
1902  at  a  cost  of  $5000)  for  the  purpose  of  better 
heating  and  tarring  the  broken  stone,  or  blast-furnace 
slag,  and  which  was  described  as  being  an  improve- 
ment on  former  methods. 

By  Hand-labor. — It  consists  of  cast-iron  plates  three- 
fourths  inch  thick  and  ten  feet  by  twenty-four  feet  in 
area,  supported  on  brick  walls  about  three  feet  high 
forming  flues,  heated  by  five  furnaces  in  which  con- 
tinuous coal  fires  are  maintained.  Crushed  stone,  or 
crushed  slag,  is  spread  over  the  hot  plates  in  a  layer 
six  inches  to  ten  inches  thick,  and  turned  two  or  three 
times,  by  hand,  with  shovels,  until  dry  and  hot,  when 
it  is  wheeled  to  a  mixing- board,  ten  feet  by  four  feet, 
where  three  wheelbarrows  full,  or  say  half  a  cubic  yard, 
is  assembled  and  hot  tar  composition  poured  over  it, 
turning  meantime  by  hand-shovels  until  every  fragment 
is  covered  with  tar.  It  is  then  put  on  a  wheelbarrow 
and  tipped  into  a  heap  where  it  is  left  to  "mature" 
for  six  to  nine  weeks.  The  tar  composition  for  treat- 
ing one  ton  of  slag  is  formed  by  boiling  together  for 
one  and  one-quarter  hours  twelve  gallons  of  crude  coal- 
tar,  two  gallons  of  creosote-oil  and  fifty-six  pounds 

101 


ROADf  PRESERVATION  AND  DUST  PREVENTION. 

of  pitch,  stirring  meanwhile.  For  crushed  stone,  the 
quantity  is  usually  one-third  less  because  of  less  absorp- 
tion. Care  must  be  used  that  the  stones,  or  slag  frag- 
ments, do  not  get  hot  enough  to  burn  the  tar  and  make 
it  brittle.  (A  simple  and  effective  rule  is  that  the  stones 
must  not  be  too  hot  to  hold  in  the  hand.) 

Five  men  thus  treat  twenty  tons,  or  say  sixteen  cubic 
yards  per  day,  the  operation  involving  the  hand-shoveling 
of  the  materials  at  least  seven  times,  after  which  it  must 
be  stored  as  stated,  before  being  again  shoveled  for  transfer 
to  the  road  for  use. 

Cost. — The  cost  at  English  prices  of  three  cents  per 
gallon  for  tar  and  creosote,  $12.50  per  ton  for  pitch, 
and  $1  per  day  for  labor,  must  have  been  at  least  $1.20 
per  ton  or  $1.44  per  loose  cubic  yard;  for  the  tarring 
of  stone  to  form  a  finished  thickness  of  six  inches,  this 
would  cost  thirty- six  cents  per  square  yard  for  the  tarring 
only,  which  is  excessive.  At  the  prices  in  the  United 
States  this  would  be  increased  sixty  per  cent,  making  it 
fifty-eight  cents  per  square  yard,  which  is  prohibitive. 

By  Machine. — In  1904  Brown  and  Clarke  built  and 
used  at  Nottingham,  England,  a  machine  weighing 
twelve  tons  and  costing  $1400,  for  heating,  tarring,  and 
mixing  mechanically,  with  the  work  of  two  men  (in- 
cluding the  engine-runner),  thirty-five  tons  of  crushed 
stone  per  day,  using  eight  gallons  of  crude  coal-tar  and 
sixteen  pounds  of  pitch  per  ton,  which,  at  the  same 
unit  prices,  cost  for  the  tarring  sixty-two  cents  per  ton 
or  seventy-four  cents  per  loose  cubic  yard,  equal  to  a 
cost  for  the  tarring  of  stone  to  form  a  finished  thickness 
of  six  inches,  of  eighteen  cents  per  square  yard  at 
English  prices,  or  twenty-nine  cents  at  United  States 
prices. 

102 


TAR-MACADAM. 

This  improved  equipment  consists  of  a  hopper  into 
which  the  crushed  stone  is  tipped  and  thence  fed  auto- 
matically into  the  longitudinal  pockets  of  an  inclined 
cylinder  with  a  worm  conveyer,  the  whole  operated  by 
a  four-horse  power  engine.  Underneath  are  two  coke 
fires  which  heat  the  cylinders  and  their  contents  and 
dry  the  stone,  and  also  heat  two  attached  tar-tanks 
which  are  mounted  on  a  saddle  over  the  revolving 
cylinder,  through  which  the  stone  passes  slowly  (mean- 
tin,  j  being  thoroughly  heated  and  dried),  and  then 
drops  into  the  trough  where  it  is  automatically  sprayed 
with  a  regulated  amount  of  heated  tar  and  is  turned 
and  mixed  by  the  worm-conveyer,  which  moves  the 
tarred  stone  to  the  upper  end  where  it  is  ready  to  be 
stored  for  future  use  as  desired.  The  quantity  of  tar 
sprayed  upon  the  stone  is  adjusted  to  the  speed  of 
the  machine,  so  that  there  is  neither  an  excess  nor  a 
deficiency. 

Cost.— As  has  been  detailed,  this  Nottingham  machine 
does  the  work  of  tarring  at  one-half  the  cost  of  the 
similar  work  done  by  the  so-called  improved  equip- 
ments for  hand-labor  at  Sheffield  and  Grimsby. 

Another  similar  plant  was  equipped  in  1906  near 
Gainsborough,  England,  by  Parry  &  Sons,  where  blue 
lias  limestone  from  their  quarries  is  crushed  and  heated 
and  treated  with  refined  tar,  with  which  tarred  limestone 
a  competitive  section  of  2300  square  yards  of  tar-macadam 
was  built  in  1906  at  a  cost  of  forty-four  cents  per  square 
yard,  including  all  materials  and  labor  complete.  This 
was  claimed  to  be  "as  good  as  the  best  tarmac." 


103 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


TARMAC. 

Tarmac  is  a  trade  name  for  blast-furnace  slag,  coated 
and  rilled  while  hot  with  heated,  refined  tar  and  tar- 
oils.  It  is  manufactured  and  laid  by  the  Tarmac  Com- 
pany of  Ettingshall,  Wolverhampton,  near  Birmingham, 
and  is  more  or  less  made  wherever  blast-furnace  slag  is 
available,  being  shipped  from  the  iron  districts  to  all 
parts  of  England. 

HISTORY. 

It  was  first  laid  in  1898  at  Newark,  near  Nottingham, 
and  the  success  there  led  to  use  elsewhere.  The  slag 
is  crushed  and  screened  into  three  sizes,  like  crushed 
rock.  It  is  dried  as  before  described,  on  iron  plates,  or 
in  rotary  cylinders,  or  is  taken  directly  from  the  blast- 
furnace while  still  hot,  and  each  size  is  separately  tar- 
red, using  twelve  to  fifteen  gallons  of  prepared,  refined 
tar  per  ton  of  hot  slag. 

The  road  at  Newark,  near  Nottingham,  just  mentioned, 
was  formerly  maintained  by  an  annual  coating  of  crushed 
granite,  until  1898,  when  it  was  covered  with  a  three 
and  one-half  inch  layer  of  the  first  "tarmac,"  which 
lasted  without  repairs  until  1905,  when  it  was  re- 
surfaced with  one  and  one-fourth  inches  of  tarmac. 
It  is  said  to  be  free  from  mud  and  dust. 

OBJECTIONS. 

Slag,  which  is  very  porous  and  absorbs  most  tar,  is 
structurally  weak  and  crushes  readily  under  traffic,  so 
that  there  is  much  room  for  choice  in  selecting  only 

104 


TAR-MACADAM. 

such  slag  as  is  best  suited  to  the  purpose,  its  irregu- 
larity making  careful  inspection  necessary.  Slag  having 
much  sulphur  or  lime  must  be  avoided.  In  making 
shipments  by  rail  during  hot  weather  it  is  sometimes 
found  that  so  much  of  the  tar  has  oozed  out  of  the  slag 
and  has  settled  in  the  bottom  of  the  car-load  that  the 
whole  needs  to  be  re-heated  and  turned  before  spreading 
in  place  upon  the  road. 

METHODS. 

The  treatment  used  to  make  tarmac  at  Grimsby 
in  1906  is  described  on  page  101,  and  is  more  or  less 
the  standard  method.  In  some  cases  the  slag  is  taken 
directly  from  the  blast-furnace  while  it  still  retains 
its  original  heat,  saving  the  expense  of  drying  it  and 
thus  producing  "tarmac"  in  its  best  form.  It  is 
deemed  best  to  store  the  tarred  slag  for  some  weeks  or 
months,  or  until  the  tar  is  absorbed  and  has  "toughened" 
as  much  as  possible,  and  also  until  any  excess  of  tar 
shall  drain  off.  Tarmac  seems  to  have  been  more  used 
than  any  other  material  in  making  the  so-called  tar- 
macadam  roads  in  England,  being  in  use  by  the  road 
authorities  of  seven  counties  from  London  to  Birmingham 
and  Sheffield,  and  also  by  the  authorities  of  eighteen 
corporations  and  boroughs,  of  twenty-eight  urban  dis- 
tricts and  six  rural  districts. 

Tarmac  Surface. — When  an  old  macadam  road  is 
surfaced  with  tarmac,  the  usual  method  is  to  remove 
all  loose  fragments  and  irregularities  and  to  make 
the  top  of  the  old  road  firm  and  with  the  regular 
crown,  and  upon  this  to  spread  the  tarmac  of  one  inch 
to  one  and  one-half  inch  size,  four  inches  deep  when 

105 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

loose,  rolling  this  to  a  finished  thickness  of  two  and  two- 
thirds  to  three  inches,  covering  the  completed  surface 
with  fine  slag  screenings  or  sand. 

Tarmac  Construction. — When  the  entire  road  is  to  be 
made  of  tarmac,  as  at  Grimsby,  it  is  laid  in  three 
layers,  each  separately  rolled  solid.  For  the  bottom 
course,  fragments  of  two  and  one-half  inch  gauge  are 
spread  four  and  one-half  inches  deep,  loose,  and  rolled 
to  three  and  one-half  inches;  over  this  is  spread  a  two- 
inch  loose  layer  of  one-inch  gauge,  which  is  rolled  to 
one  inch;  over  this  is  spread  a  one-inch  loose  layer  of 
three-eighths  inch  gauge,  which  is  rolled  to  one-half 
inch,  the  whole  making  a  finished  thickness  of  five 
inches  at  the  center  and  three  inches  at  the  sides.  The 
completed  surface  is  then  covered  with  fine  slag  screen- 
ings, or  fine  sand,  as  in  certain  stages  of  weather  it  other- 
wise becomes  very  slippery.  The  whole  work  must  be 
done  in  dry  weather,  and  preferably  in  warm  weather. 
The  water-proof  character  of  the  road  is  such  that  the 
crown  or  camber  may  be  half  that  required  for  ordinary 
macadam. 

Comparative  cost. — In  comparative  constructions  in 
1907  at  Gainsborough  (not  far  from  Nottingham  where 
tar-macadam  originated)  a  "tarmac"  road  coating  four 
inches  thick  when  loose  and  two  and  two-thirds  inches 
to  three  inches  thick  when  solid,  cost  fifty  cents  per  square 
yard,  while  tar-macadam  of  blue  lias  limestone  of  the 
same  thickness  cost  forty-four  cents  per  square  yard,  or 
fourteen  per  cent  more  for  tarmac  than  for  tar-macadam. 
At  the  same  time  and  place,  a  coating  of  water-worked 
whinstone  (i.e.,  ordinary  macadam)  of  half  this  thick- 
ness cost  twenty- two  cents  per  square  yard,  or  the  same 
as  the  tarred  limestone  for  the  same  total  cubic  quantity. 

106 


TAR-MACADAM. 


CRUSHED    STONE    TAR-MACADAM. 

Tar-macadam  roads  in  England  when  made  of  crushed 
stone  are  usually  of  limestone,  or  of  granite,  or  of  trap, 
basalt,  or  whinstone  (three  names  for  similar  rock),  the 
extent  of  use  being  in  about  the  order  named;  a  hard, 
tough  rock  which  breaks  with  a  rough  fracture  being 
preferred  when  other  conditions  are  equal.  Preference 
is  sometimes  expressed  for  a  porous  rock  which  can 
absorb  the  tar,  but  the  evident  weakness  of  such  mate- 
rial makes  it  undesirable  for  road-work. 

METHODS. 

In  cases  where  an  old  macadam  roadway  is  to  be 
surfaced  with  tarred  stone,  the  old  road  is  stripped 
to  the  desired  grade  and  the  low  places  made  good. 
The  tarred  stone  of  two  and  one-quarter  to  two  and  one- 
half  inches  gauge  is  spread  in  a  loose  layer  six  inches 
deep  and  is  rolled  to  four  inches;  this  is  covered  with 
a  two-inch  loose  layer  of  three-quarter  inch  to  one-inch 
gauge  tarred  stone,  rolled  to  fill  the  interstices ;  the  whole 
when  solid  is  covered  with  a  light  coat  of  slag-screenings 
or  sand.  A  surface  treatment  of  refined  tar  applied  once 
in  two  or  three  years  serves  to  keep  such  a  tar-macadam 
road  in  good  condition  with  ordinary  traffic. 

In  some  cases  crushed  stone  without  tar  is  spread 
and  rolled  dry,  and  is  then  grouted  or  flushed  with 
boiling  tar  or  bituminous  mixture  of  tar,  pitch  and  oil, 
as  described ;  a  covering  of  half-inch  chippings  or  screen- 
ings of  stone  being  added  and  rolled.  This  method 
chills  the  boiling  tar  or  mixture  on  the  surfaces  of  the 
cold  stones,  reducing  its  wearing  qualities,  and  it  also 

107 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

usually  deposits  an  excessive  quantity  of  tar  at  the  bottom 
of  the  mass  of  stone;  in  hot  weather  this  excess  works 
to  the  surface  and  makes  trouble.  Such  construction 
is  not  desirable,  and  is  so  described  on  page  118. 

COMPARATIVE    COSTS    OF    TAR-MACADAM. 

Local  conditions  vary  so  much  that  it  is  useless  to 
compare  costs  at  different  places.  Actual  results  at 
places  where  both  the  ordinary  macadam  and  the  tar- 
macadam  have  been  used  are  instructive. 

In  the  Ethington  district,  near  Manchester,  England, 
tar-macadam  has  been  extensively  used  since  1894, 
and  has  there  been  found  to  cost  twice  as  much  as 
ordinary  macadam  and  to  last  four  times  as  long  before 
needing  renewal,  meantime  having  little  dust  or  mud. 

In  Northumberland,  tar-macadam  cost  one-third  more 
than  ordinary  macadam  when  crude  means  of  hand- 
mixing  were  used  to  tar  the  stone.  The  general  use  of 
mechanical  mixing,  as  described  on  page  102,  is  expected 
to  reduce  the  cost  of  tarred  roads  to  rates  little  greater 
than  the  cost  of  dust -and -water  built  or  ordinary 
macadam.  In  1894  and  1895  J.  George-Powell,  now 
engineer  of  the  Godstone  district,  near  London,  built  tar- 
macadam  roads  in  Pocklington,  East  Yorkshire,  near 
York,  which  roads  were  still  in  good  condition  ten  years 
after.  In  1905,  being  still  interested  in  tar  construction, 
Mr.  Powell  made  a  drive  of  1200  miles  through  the  nine 
counties  north  of  London,  and  found  many  tar-macadam 
roads,  some  many  years  old,  and  some  recently  built, 
and  all  of  them  were  noticeable  for  their  comparative 
freedom  from  dust  and  mud.  The  workmen  employed 
upon  them  gave  replies  indicating  considerable  decrease 

108 


TAR-MACADAM. 

in  the  cost  of  maintenance.  His  extended  experience 
led  him  to  conclude  that  tar-macadam  roads  can  be 
made  to  last  seven  to  eight  years,  with  comparative 
freedom  from  dust  or  mud  and  at  less  final  cost,  as  com- 
pared with  three  years'  life  for  ordinary  macadam  roads, 
which  always  have  either  dust  or  mud. 

Tar-macadam  made  at  Sheffield  (where  the  method 
has  been  used  for  the  past  forty  years)  with  the  base  course 
of  tarred  limestone  and  the  top  course  of  tarred  slag,  is 
said  by  Charles  Froggatt  Wike,  M.  Inst.  C.  E.,  county 
engineer,  whose  charge  includes  fifteen  miles  of  long  used 
tar-macadam  roads,  to  cost  the  same  per  square  yard 
as  does  the  ordinary  macadam  made  of  crushed  granite; 
the  cost  of  tarring  the  limestone  and  slag  being  offset 
by  their  less  original  cost  as  compared  with  that  of 
granite,  the  final  cost  being  fifty-four  to  sixty  cents  per 
square  yard,  exclusive  of  foundations.  He  states  that  a 
typical  suburban  road  of  tar-macadam,  fairly  flat  and 
having  considerable  traffic,  shows  an  average  annual 
charge,  including  the  initial  cost  distributed  over  four- 
teen years  and  maintenance,  of  eight  cents  per  square 
yard  per  year.  On  another  tar-macadam  road  with 
lighter  traffic,  the  average  annual  charge,  including 
initial  cost  distributed  over  the  same  term,  and  main- 
tenance, has  been  five  cents  per  square  yard.  Mr.  Wike 
urges  the  importance  of  keeping  tar-macadam  roads  in 
good  order,  and  of  tar-painting  the  surface  every  three 
or  four  years,  or  as  soon  as  they  get  rough.  Tar-mac- 
adam made  at  Nottingham,  where  all  the  materials  are 
at  hand,  costs  forty-two  cents  to  forty-eight  cents  per 
square  yard.  Similar  roadways  made  at  Battersea  in 
London,  where  all  the  materials  must  be  brought  from  a 
distance,  cost  eighty-four  cents  to  $1.08  per  square  yard 

109 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

In  the  annual  re-surfacing  in  June  and  July,  1905,  of 
the  sixty-four  feet  roadway  on  the  Victoria  Embankment 
in  London,  where  the  traffic  is  both  fast  and  heavy, 
comparative  one  hundred  feet  sections  of  tarred  granite, 
tarred  limestone  and  tarred  slag  were  laid,  each  of  six 
inches  finished  thickness.  Crude  methods  must  have 
been  used,  as  it  took  a  month  and  a  half  to  lay  the  total 
of  2100  square  yards.  The  granite  failed  at  once  and 
the  limestone  in  three  months,  and  both  were  replaced 
by  ordinary  macadam  of  Guernsey  granite  in  November 
of  the  same  year.  The  tarred  slag  was  somewhat  better. 
The  failure  of  the  tarred  granite  was  attributed  to  wet 
weather  during  construction.  The  limestone  and  the 
slag  were  laid  in  dry  weather.  The  costs  were  $1.08 
per  square  yard  for  the  tarred  limestone  and  the  tarred 
slag,  and  $1.26  per  square  yard  for  the  tarred  granite. 

In  1908  Arthur  Brown,  M.  Inst.  C.  E.,  city  engineer 
of  Nottingham  (where  tar-macadam  is  best  known),  in  a 
paper  read  before  the  Royal  Sanitary  Institute,  stated 
the  cost  of  new  tar-macadam,  including  foundations,  to 
be  eighty-four  cents  per  square  yard,  where  ordinary 
macadam,  including  foundations,  costs  sixty  cents  to 
sixty-six  cents  per  square  yard.  This  tends  to  confirm 
the  estimate  made  on  page  99  and  elsewhere,  that 
tarring  under  average  conditions  increases  the  cost 
one-third.  Mr.  Brown  describes  tar-macadam  as  being 
noiseless  and  dustless,  but  as  being  conducive  to  side- 
slip in  "greasy"  weather.  It  has  been  said  that  tarred 
surfaces  were  unsafe  on  steep  grades,  but  a  ten  per  cent 
grade  in  Nottingham  is  used  by  heavily  loaded  drays 
passing  down,  aided  by  sanding  when  needed,  which 
agrees  with  the  experience  at  Tiverton,  Rhode  Island,  as 
described  on  page  85. 

110 


TAR-MACADAM. 


GLADWELL    SYSTEM. 

The  "Glad well"  system,  mentioned  on  page  15,  is  a 
method  of  surfacing  macadam  roads,  either  old  or  new 
ones,  with  a  tar-macadam  top  which  gives  some  of  the 
effects  of  tar-macadam,  as  described,  and  at  a  less  cost 
which  will  probably  lead  to  its  general  use. 

SUMMARY. 

It  consists  in  imbedding  a  two-stone  course  of  un- 
tarred  clean,  crushed  stone  (usually  two-inch  gauge) 
in  and  between  two  layers  of  tarviated,  one-quarter  inch 
gauge,  dustless  stone  chips,  which  form  a  matrix  which 
is  worked,  by  judicious  rolling,  into  the  spaces  between 
the  stone  fragments  from  below  upward  and  from  above 
downward,  finally  sealing  the  surface  so  as  to  be  water- 
proof by  hot  tarvia  "A"  and  granite  drippings, 

HISTORY. 

The  system  was  devised  by  Arthur  Gladwell,  who 
has  charge  of  road  construction  and  maintenance  at 
Eton,  near  Windsor,  England,  and  was  first  used  by  him 
on  the  road  at  Stoke  Poges  in  July,  1906.  It  has  since 
been  successfully  used  on  the  roads  along  the  Thames 
in  that  vicinity,  and  elsewhere  in  England.  Its  low 
cost  and  ease  of  construction,  and  especially  the  fact 
that  most  of  the  work  may  be  done  in  ordinary 
weather,  will  no  doubt  lead  to  its  extensive  use  in  the 
United  States. 
\£  ;—.•-•-  .  ::•;  .•'.;  '  ,•  -  ...-".  I  Jj 

111 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


METHOD. 

The  road  to  be  surfaced  must  be  made  regular  and 
firm,  the  usual  crown  or  camber  may  be  flattened  if 
desired,  and  the  surface  of  the  foundation  must  be  kept 
cleanly  brushed  as  the  work  proceeds.  For  the  bitu- 
minous binder  or  matrix,  provide  clean  granite  chippings, 
free  from  dust  and  passing  a  quarter-inch  sieve,  and 
thoroughly  dried  in  a  heater. 

Tarring. — While  still  warm,  but  not  hotter  than  100° 
F.,  these  chippings  are  mixed  with  tarvia  "A,"  heated 
to  175°  F.,  in  the  average  proportion  of  fifteen  gallons 
of  tarvia  per  cubic  yard  of  chippings,  less  tarvia  being 
required  in  warm  weather  and  more  in  cold  weather. 
Crude  tar  cannot  safely  be  used,  and  tarvia  is  specially 
advised  by  Mr.  Glad  well.  The  warm  chips  and  the 
hot  tarvia  are  mixed  gradually  like  concrete  until  they 
form  a  plastic  mass,  which  is  preferably  used  at  once, 
but  which  may  be  kept  forty-eight  hours  or  longer, 
provided  the  hardened  surface  of  the  pile  is  sepa- 
rated and  worked  over  with  hot  tarvia.  (Evidently  a 
rotary  concrete  mixer  could  be  well  utilized  for  making 
this  mixture.) 

Spreading. — This  matrix  is  spread  in  a  three-quarter 
inch  layer  upon  the  prepared  foundation,  forming  the 
"sub-binder"  over  about  six  feet  in  length  of  the  road, 
and  for  about  half  its  width,  covering  about  forty-six 
square  yards  of  surface  with  one  cubic  yard  of  the  tarred 
material.  It  should  be  spread  evenly  and  lightly,  and 
must  on  no  account  be  trampled  upon  or  consolidated  in 
any  way  until  it  has  been  covered  evenly  with  a  two-stone 
course  of  two-inch  to  two  and  one-quarter  inch  clean, 

112 


TAR-MACADAM. 

dry,  crushed  stone,  a  loose  cubic  yard  of  two-inch  gauge 
stone  covering  about  fourteen  square  yards  of  surface. 
Use  stone  forks  (not  shovels)  to  spread  the  stone,  so  as 
to  leave  out  all  small  pieces  and  flakes  and  dust.  Bring 
this  layer  of  stone  to  within  six  inches  of  the  forward 
end  of  the  " sub-binder"  already  laid,  and  then  lay 
another  three-foot  length  of  "  sub-binder,"  following 
with  the  two-stone  coat,  and  always  arranging  so  that 
the  workmen  do  not  trample  upon  the  " sub-binder"; 
also,  leave  a  loose  edge  of  both  courses  at  the  center  line 
of  the  road  to  insure  a  good  joint  when  the  other  half  is 
built  the  next  day.  When  the  whole  width  of  road  must 
be  done  at  one  operation,  scarify  the  center  or  traffic 
track  for  say  twelve  feet  width,  and  remove  the  loosened 
materials  for  use  elsewhere.  Sweep  the  scarified  surface 
clean,  and  then  spread  the  " sub-binder"  and  the  two- 
stone  coat,  as  before  described. 

Rolling. — The  two-stone  coat  being  ready  on  a  section 
of  twenty-five  or  thirty  yards  in  length  of  the  road, 
begin  rolling  at  once,  using  a  fairly  light  steam-roller 
moving  at  slowest  speed  in  order  to  press  the  stones 
gently  down  into  the  matrix,  and  at  the  same  time  to 
draw  the  matrix  upward  between  the  fragments.  This 
is  not  accomplished  so  well  by  a  heavy  roller  as  by  a 
light  one  judiciously  used.  As  soon  as  the  " sub-binder" 
is  seen  to  be  working  up  between  the  stones,  sprinkle 
some  of  the  same  bituminous  material  lightly  over  the 
top  of  the  stones  and  carefully  brush  it  into  the  surface 
voids  until  they  are  fairly  well  filled,  the  binding  mate- 
rial or  matrix  thus  working  both  upward  and  downward 
under  the  action  of  the  roller  until  the  new  surface  of 
the  road  is  solid.  Thus  much  of  the  construction  may 
be  done  in  any  ordinary  weather  and  need  not  be  con- 

113 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

fined  to  the  warm  and  dry  weather  usually  required 
for  tarred  construction. 

Finishing. — For  the  completion  or  "  surface  sealing," 
warm,  dry  weather  is  essential.  It  is  useless  to  attempt 
it  during  wet  weather.  One-sixth  gallon  of  heated 
tarvia  "A"  per  square  yard  of  surface  may  be  sprayed 
over  the  surface  by  one  of  the  machines  described  on 
page  70,  or  it  may  be  applied  otherwise,  the  fresh 
surface  being  at  once  covered  with  a  one-quarter  inch 
layer  of  clean,  dry,  quarter-inch  gauge  granite  or  trap 
screenings,  of  which  one  cubic  yard  will  cover  180 
square  yards  of  surface.  The  road  should  then  be  well 
rolled.  If  it  is  desirable  to  complete  the  surface  sealing 
by  hand  as  the  work  progresses,  as  is  often  the  case, 
this  may  be  done  with  hand-watering  cans  having 
V-shaped  lip-outlets,  spreading  one-quarter  to  one-half 
gallon  of  heated  tarvia  per  square  yard  and  covering 
it,  as  before  described. 

This  description  provides  for  a  finished,  Gladwellized 
surface  of  two  and  three-quarter  inches  to  three  inches 
finished  thickness.  If  a  thicker  coating  is  wanted,  omit 
the  "top-sealing"  from  the  first  course,  apply  another 
layer  over  it,  and  "top-seal"  the  last.  If  a  thinner  coat 
is  wanted,  as  for  roads  having  light  traffic,  reduce  the 
size  of  the  stones  forming  the  "two-stone"  layer,  and 
reduce  the  thickness  of  the  "sub- binder"  proportion- 
ately. 

Cost. — On  the  roads  thus  built  by  Mr.  Gladwell  at 
Slough  and  by  George  W.  Manning  at  Staines,  both  near 
Windsor,  England,  the  greater  cost  as  compared  with 
that  of  an  ordinary  macadam  surface  has  been  seven 
cents  per  square  yard.  The  lesser  thickness  required 
reducing  the  quantity  of  stone  and  lowering  the  cost. 

114 


TAR-MACADAM. 


The  inventor  finds  that  with  proper  organization  450 
square  yards  of  surface,  or  250  feet  of  a  sixteen- feet 
road,  can  easily  be  completed  in  a  day. 

At  prices  in  the  United  States  the  cost  should  not  be 
more  than  the  cost  of  dust-and-water  built  macadam 
plus  twenty  per  cent. 

Opinions. — The  method  is  commended  by  H.  Howard 
Humphreys,  Assoc.  M.  Inst.  C.  E.,  in  1908,  in  a  paper 
read  before  the  Society  of  Road-traction  Engineers  in 


SPREADING  SCREENINGS  OVER  TARVIA  (Jackson,  Tenn.). 

London.  Practically  a  similar  construction  is  proposed 
by  Logan  Waller  Page,  Director  of  the  United  States 
Office  of  Public  Roads,  as  detailed  on  page  116. 

TAR-MACADAM    IN   THE   UNITED   STATES  AND   CANADA. 
SUMMARY. 

There  is  as  yet  no  general  use  of  tar-macadam  on 
rural  roads,  such  work  being  so  far  done  only  on  a  small 
scale  in  an  experimental  way  by  the  road  departments  of 

115 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

some  of  the  States,  and  by  a  few  towns  and  villages. 
The  use  of  the  high-class  bitulithic  and  its  imitations 
has  been  confined  to  urban  and  suburban  streets.  The 
United  States  Office  of  Public  Roads  did  some  useful 
work  at  Jackson,  Tennessee,  in  1905,  and  the  results 
as  published  by  Director  Page  have  been  generally  read 
and  used  as  the  basis  for  other  experiments.  The  re- 
port says: 

"A  tarred  street  is  dustless  in  the  same  sense  that  an  asphalt 
street  is  dustless,  though  a  fine  sandy  powder  wears  off  as  in  the 
case  of  asphalt.  In  driving  over  a  tarred  macadam  road,  the  lessen- 
ing of  vibration  and  noise  is  at  once  noticeable.  The  ordinary 
macadam  produces  a  constant  succession  of  slight  jars  upon  a 
steel-tired  wheel  and  there  is  a  relief  felt  at  once  in  driving  upon  a 
road  treated  with  tar." 

The  United  States  Office  of  Public  Roads  continued 
to  give  special  attention  to  the  subject  during  1906  and 
1907,  and  in  circular  No.  89,  issued  April  20,  1908, 
Director  Page  expressed  the  opinion  elsewhere  quoted 
that  surface  treatments  were  palliatives  rather  than  dust- 
preventives  and  that  a  more  lasting  method  would  be 
"the  use  of  well-tarred  sand  as  part  of  the  binding  mate- 
rial and  to  fill  voids,"  applying  a  layer  of  such  tarred 
sand  to  the  rolled  base-course,  over  which  the  top  course 
should  be  spread  and  rolled  until  the  tarred  sand  should 
work  down  into  the  base-course  and  up  into  the  top- 
course.  The  surface  being  then  finished  by  an  applica- 
tion of  tar  covered  with  fine  chips  or  sand  and  rolled  until 
smooth  and  uniform.  This  suggested  method  is  prac- 
tically the  same  as  the  "Gladwell"  system,  described  and 
commended  on  page  111. 

In  Canada,  tar-macadam  has  been  used  to  a  consider- 
able extent  by  the  cities  of  Hamilton,  Toronto,  and 

116 


TAR-MACADAM. 

Ottawa.  Hamilton  (located  midway  between  Buffalo 
and  Toronto)  built  several  miles  of  tar-macadam  in  the 
English  method  as  early  as  1880  and  has  maintained 
and  extended  it  since  to  a  total  of  nine  miles  of  thirty- 
feet  roadways  in  1908  at  initial  costs  of  from  seventy- 
nine  cents  to  $1.06  per  square  yard.  Toronto  has  built 
since  1902  about  the  equivalent  of  six  miles  of  thirty- 
feet  roadways  costing  about  $1.50  per  square  yard. 
Ottawa,  since  1902,  has  built  about  half  as  much,  costing 
from  $1.24  to  $1.57  per  square  yard.  The  latter  being 
particularly  well  built  and  successful  in  being  clean 
and  dustless,  but  being  too  costly  for  other  than  city 
streets. 

METHODS. 

In  Rhode  Island.— In  1906  and  1907  the  State  Board 
of  Public  Roads  of  Rhode  Island  used  tar  in  constructing 
a  macadam  road  on  a  main  State  highway,  near  Charles- 
town,  in  method  described  by  Assistant  Engineer  Arthur 
W.  Blanchard.  The  road  is  of  special  interest  because 
it  is  part  of  a  main  trunk  line  between  New  York,  New- 
port, Providence,  and  Boston,  and  is  therefore  subject 
to  the  maximum  of  high-speed  motor-car  travel.  The 
macadam  was  built  in  much  the  usual  way  with  the 
addition  of  tar.  The  bottom  layer  of  one  and  one- 
quarter  inch  to  two  and  one-half  inch  crushed  stone, 
six  inches  loose  and  rolled  dry  to  four  inches,  was  sprinkled 
freely  over  the  top  with  hot  tar  from  dippers.  Half -inch 
to  one  and  one-quarter  inch  crushed  stone  was  then 
mixed  with  hot  tar  by  turning  by  hand-shovels  and  rakes 
on  dumping-boards  until  all  surfaces  of  stone  were  fully 
coated,  when  it  was  at  once  spread  in  a  three-inch  loose 

117 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

layer  and  rolled  to  two  inches  finished  thickness.  A 
thin  coating  of  screenings  and  dust  was  then  spread 
and  rolled  upon  the  freshly  tarred  stone.  The  whole 
work  was  done  only  when  perfectly  dry,  and  was  begun 
and  completed  each  fair  day  at  the  rate  of  one  hundred 
lineal  feet,  or  154  square  yards  per  ten  hours. 

Cost. — Five  extra  men  did  the  tarring  at  a  cost  for 
labor  of  six  cents  per  square  yard.  One  and  one- 
seventh  gallons  of  tar  per  square  yard  was  used, 
costing  ten  cents  per  gallon,  but  this  was  partly  offset 
by  a  saving  of  one  and  three-quarters  cent  per  square 
yard  from  not  using  any  water,  making  a  total  cost 
for  the  tarring  of  sixteen  and  one-quarter  cents  per 
square  yard.  The  road  thus  built  endured  the  severe 
winter  of  1906-1907,  and  the  traffic  through  1907, 
without  showing  perceptible  change  and  without 
dust. 

On  the  Narragansett  Pier  road,  in  1907,  tarvia  "A" 
was  used  in  constructing  a  new  tar-macadam  road. 
The  lower  course  of  six  inches,  loose,  of  untarred  crushed 
trap  was  rolled  solid  to  four  inches  in  the  usual  way 
but  without  water,  and  upon  it  was  spread  two  and 
one-half  inches  to  three  inches  of  dry,  untarred  half-inch 
to  one  and  one-half  inch  crushed  trap,  which  was  lightly 
rolled.  The  tarvia,  which  had  been  heated  in  tar-kettles, 
was  then  poured  upon  the  surface  of  the  lightly  rolled 
top-course  and  was  allowed  to  penetrate,  going  in  one 
to  two  inches.  Eight- tenths  gallon  to  one  and  six- tenths 
gallons  per  square  yard  was  used,  varying  according  to 
the  amount  of  rolling  and  the  size  of  the  stone.  Trap 
screenings,  half-inch  to  dust,  was  then  spread  over  the 
tarred  surface  three-quarters  of  an  inch  deep,  and  the 
whole  was  then  rolled  until  firm  and  smooth.  The  only 

118 


TAR-MACADAM. 

added  cost  was  for  the  tarvia.     Similar  English  work  is 
described  on  page  107  as  being  undesirable. 

In  Massachusetts. — The  comparative  cost  of  tar-mac- 
adam and  ordinary  dust-and-water  built  macadam  in 
Massachusetts  is  clearly  discussed  by  Assistant  Engi- 
neer H.  C.  Poore,  in  the  1908  report  of  the  Massachu- 
setts Highway  Commission,  estimating  that  a  dust- 
and-water- built  macadam  of  five  inches  finished  thick- 
ness costs  fifty-three  and  one-third  cents  per  square 
yard,  and  that  a  similar  tar-macadam  road  costs 
sixty- eight  and  one-half  cents  per  square  yard,  equal 
to  the  cost  of  the  ordinary  macadam  plus  twenty-eight 
per  cent.  The  tar-macadam  estimated  upon  consists 
of  an  untarred  base-course  bound  and  filled  with  dry 
screenings  or  sand  and  rolled  until  firm  and  three 
inches  thick.  This  to  be  covered  with  a  two-inch 
finished  thickness  of  tarred  top-course  of  half-inch  to 
two-inch  stones  (using  a  rotary  concrete-mixer  to  coat 
the  stones  with  two-thirds  gallon  of  tar  for  one-ninth 
cubic  yard  of  loose  stone,  or  enough  to  make  one  square 
yard  of  top-course).  This  course  after  rolling  to  be 
covered  by  a  top  dressing  of  "pea"  stone,  or  coarse 
screenings,  treated  after  spreading  and  rolling  with  four- 
tenths  gallon  of  tarvia  "  A"  per  square  yard,  which  is  also 
rolled.  These  estimates  are  based  upon  the  assumptions 
that  the  subgrade  is  completed  ready  to  receive  the 
macadam;  that  the  crushed  stone  costs  $1.25  per  ton 
(or  about  $1.50  per  cubic  yard),  delivered;  that  tarvia 
delivered  on  car  costs  seven  and  one-half  cents  per 
gallon,  and  that  the  labor  of  tarring  the  surface  costs 
two  cents  per  square  yard.  This  construction  is  ex- 
pected to  eliminate  dust  and  prevent  ravelling  at  a  reason- 
able cost. 

119 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

Kettles  for  Heating — Mr.  Poore  commended  the  use 
of  500-gallon  kettles  to  heat  the  tar  in  preference  to 
smaller  ones  (see  page  87),  and  advised  that  the  wheels 
of  the  kettles  should  be  fitted  with  five-inch  tires,  and 
that  there  should  be  spigots  at  each  end  of  the  kettles 
so  that  all  of  the  contents  might  be  run  out  when  on 
inclines,  and  that  the  hose  should  terminate  in  a  funnel 
attachment  to  deliver  the  hot  tar  in  a  broad,  thin 
stream. 


120 


ROCK-ASPHALT  MACADAM. 


SUMMARY. 

This  construction  gives  good  results,  but  the  cost  of 
transportation  has  limited  its  use  to  the  vicinities  of 
the  natural  formations  of  the  peculiar  sandstones  and 
limestones  which  are  impregnated  with  bitumen  and 
are  known  as  "  rock-asphalts." 

The  natural  formations  which  occur  in  Arkansas, 
Indian  Territory,  and  Kentucky,  are  sand-rock  im- 
pregnated with  a  proportion  of  bitumen  varying  from  a 
trace  to  a  maximum  of  thirteen  per  cent,  six  per  cent 
being  about  the  least  useful  proportion. 

The  European  supplies  are  those  of  France,  Sicily,  and 
Switzerland,  and  are  bituminous  limestones  formed  by 
natural  combinations  of  about  twelve  per  cent  of  bitumen 
with  about  eighty-eight  per  cent  of  amorphous  carbonate 
of  lime,  and  were  first  used  for  roads  in  Paris  in  1854, 
and  since  then  have  made  the  comparatively  small 
extents  of  asphalt  pavements  in  European  cities,  being 
too  costly  for  general  use  and  much  more  slippery  than 
the  similar '  city  pavements  made  from  the  American 
sand-rock  asphalts,  which  are  also  costly. 

121 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


METHODS. 

For  less  costly  roadways  in  the  cities  of  the  south- 
western States  of  the  United  States,  sand-rock  asphalts 
from  the  formations  in  Arkansas  and  Kentucky  have 
been  combined  with  ordinary  macadam  in  an  effective 
way,  which  is  described  by  Walter  F.  Reichardt,  Assoc. 
M.  Am.  Soc.  C.  E.,  city  engineer  of  Little  Rock, 
Arkansas,  in  a  paper  read  before  the  1906  meeting  of 
the  American  Society  of  Municipal  Improvements.  He 
has  used  the  several  kinds  named  and  finds  the  Arkansas 
sand-rock  asphalt  to  be  the  easiest  to  use,  it  being  richer 
in  bitumen  and  exceptionally  good  for  rock-asphalt 
macadam.  At  Little  Rock,  Arkansas,  the  method  is  as 
follows : 

CITY    STREETS. 

The  subgrade  is  prepared  in  the  manner  usual  for  a 
good  macadam  road,  using  special  care  to  remove  all 
soft  spots  and  to  roll  thoroughly. 

Spreading. — The  usual  three-inch  to  four- inch  base- 
course  of  one  and  one-half  inch  to  two  and  one-half 
inch  ordinary  crushed  stone  is  spread,  filled  with 
dry  sand,  and  rolled  without  water.  Over  this  is 
spread  and  rolled,  dry,  another  three-inch  finished 
thickness  of  the  same  sizes  of  crushed  stone  as  the 
base,  but  without  the  sand  filler.  (The  crushed  stone 
used  is  trap,  granite,  limestone,  or  chert,  whichever 
is  most  available.)  Over  this  second  course  is  spread 
a  top  layer  sufficient  to  fully  cover,  formed  of  equal  parts 
of  ground  sand-rock  asphalt  and  half-inch  to  one-inch 
crushed  stone. 

122 


ROCK-ASPHALT  MACADAM. 

Rolling. — This  layer  is  rolled  with  a  heavy  steam- 
roller until  firm  and  smooth;  dry  Portland  cement 
is  swept  over  the  surface  and  the  road  is  opened  to 
traffic. 

Results. — The  pavement  is  not  slippery,  because  the 
fragments  of  stone  imbedded  in  the  ground  sand- 
rock  asphalt  give  a  good  foothold.  It  needs  care  and 
must  be  kept  clean. 

Cost.— Its  cost  in  Little  Rock  has  been  $1.40  per 
square  yard,  entirely  preventing  its  use  on  other  than 
city  streets.  A  cheaper  and  more  generally  useful  me- 
thod is  the  following: 

SUBURBAN  ROADS. 

In  1907  the  United  States  Office  of  Public  Roads, 
Logan  Waller  Page,  director,  made  an  experimental 
road  at  Bowling  Green,  Kentucky  (as  described  in 
Cir.  No.  89,  of  April  20,  1908),  using  Kentucky  sand- 
rock  asphalt,  in  which  bitumen  ranged  in  proportion 
from  six  per  cent  to  eight  per  cent  with  a  maximum 
of  twelve  per  cent. 

Kentucky  Sand-rock  Asphalt. — This  is  quarried  like 
other  rock  and  is  crushed  in  the  usual  way  into  frag- 
ments to  pass  a  two-inch  ring,  and  the  total  product 
of  the  crusher  is  then  taken  to  a  series  of  roll-crushers 
which  reduce  it  to  a  mass  of  separate  grains  of  sand, 
each  fully  coated  with  a  film  of  bitumen  sufficient 
to  cause  the  grains  to  adhere  under  pressure  and 
giving  the  sand  a  rich,  dark-brown  color.  (In  this 
condition  it  costs  $5  per  ton  f.o.b.  cars  at  Bowling 
Green,  Kentucky,  one  ton  being  equal  to  twenty-seven 
cubic  feet  loose  measure.)  If  this  sand  is  warmed  in 

123 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

the  hand,  the  bitumen  becomes  soft  and  semi-fluid,  so 
that  the  grains  separate  of  their  own  weight,  but  when 
chilled  (to  about  60°  F.  or  less)  after  compacting,  it 
becomes  hard  and  tough. 

On  an  old  roadbed  reformed  and  crowned,  crushed 
limestone  of  one  inch  to  one  and  one-half  inch  size, 
was  spread  four  inches  deep  and  rolled  once,  dry,  merely 
to  turn  down  the  sharp  edges  and  to  form  an  even  sur 
face.  (This  reduced  the  voids  to  probably  about 
twenty-five  per  cent.) 

Spreading. — The  ground  sand-rock  asphalt  above 
described,  was  then  spread  to  a  depth  of  one  and  one- 
half  inches  over  this  undisturbed  surface,  being  thrown 
on  with  shovels  from  wagons  or  dumping-boards  at  one 
side  of  the  road,  one  ton  thus  covering  twenty-four  and 
one-half  square  yards.  Care  was  taken  to  break  all 
lumps  of  the  ground  sand-rock  asphalt  and  to  work  it 
into  the  interstices  of  the  crushed  stone. 

Rolling. — Meantime  the  steam-roller  was  kept  moving 
back  and  forth,  working  always  parallel  with  the  axis 
of  the  roadway  and  from  the  outer  edge  to  the  center; 
after  the  fourth  or  the  fifth  rolling,  the  sand-rock  asphalt 
was  forced  into  the  voids  and  the  surface  became  firm. 
The  behavior  of  the  ground  sand-rock  asphalt  varied 
with  the  temperature,  the  bituminous  sand  working  into 
hard,  rounded  lumps  in  the  early  morning  when  the 
temperature  was  about  65°  F.,  and  then  spreading 
smoothly  and  compacting  evenly  as  the  temperature 
rose  to  70°  and  75°  F.  and  upward.  A  light  rain  occur- 
ring at  65°  F.,  impeded  work,  and  portions  which  were 
then  built  did  not  compact  and  become  hard  for  several 
hours  after  others  built  later. 


124 


ROCK-ASPHALT  MACADAM. 

Results. — The  road  when  opened  to  traffic  rutted  badly 
under  heavy  loads  at  first,  and  was  also  seriously  cut  by 
hoofs.  These  bad  features  disappeared  gradually  after 
three  or  four  days,  and  no  trace  of  the  ruts  or  the  cuts 
remained  at  the  end  of  a  week,  when  the  road  looked 
like  a  sheet-asphalt  pavement  which  had  been  some- 
time used.  After  four  months  it  had  undergone  no  ap- 
preciable change,  and  incisions  into  the  surface  showed 
no  drying  nor  hardening  of  the  bitumen,  the  sand  particles 
moving  as  formerly  when  warmed  in  the  hand.  The 
pavement  thus  formed  is  dustless  and  the  surface  shows 
no  appreciable  wear. 

Cost. — The  total  cost  for  material  and  labor  (including 
shaping  of  subgrade  and  buying  ground  sand-rock 
asphalt  and  crushed  stone)  was  forty-seven  and  two- 
third  cents  per  square  yard,  or  about  the  cost  of  similar 
thickness  of  ordinary  dust-and  water  built  macadam. 

It  is  evident  that  this  bituminous  sand  formed  by 
crushing  the  twelve  per  cent  sand-rock  asphalt  would  be 
well  suited  to  use  in  the  Gladwell  system,  described  on 
page  111. 

Sheet  Asphalt. — This  bituminous  sand  produced  by 
crushing  and  rolling  Kentucky  sand-rock  asphalt  has 
been  used  in  the  United  States  to  make  sheet-asphalt 
since  1890-1892  when  ten  miles  on  fifty-two  streets  were 
paved  with  it  in  Buffalo  under  five-year  guarantees;  the 
results  were  good,  the  repairs  during  eleven  years  aver- 
aging one  cent  per  square  yard  per  year.  In  San  Fran- 
cisco, Front  Street  was  thus  paved  in  1890  and  was  in 
good  condition  without  repairs  after  eleven  years  of 
heavy  use. 

Methods. — To  form  these  pavements,  the  bituminous 
sand  produced  by  grinding  the  rock  is  heated  to  300 

125 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

degrees  F.,  and  is  spread  hot  directly  upon  the  clean, 
dry,  six-inch  concrete  base  where  it  is  rolled  and  rammed 
into  a  compressed  layer  two  inches  thick.  No  "flux" 
and  no  "binder-coat"  is  needed,  the  bituminous  sand 
forming  the  entire  surface.  The  cost  was  about  the 
same  as  the  more  common  artificial  sheet-asphalt  or 
$1.40  to  $2.00  per  square  yard  including  the  usual  con- 
crete base  and  the  guarantee. 

Binder  for  Macadam. — The  success   in  this  use   indi- 
cates its  availability  as  binder  for  macadam. 


126 


BITULITHIC    PAVEMENT. 


SUMMARY. 

This  is  the  best  known  combination  of  crushed  stone 
and  bituminous  binder,  and  is  composed  of  fragments 
of  stone  which  are  held  firmly  and  free  from  attrition, 
and  hence  form  no  dust.  It  differs  from  other  bitumin- 
ous macadams  in  that  the  proportions  of  the  several 
sizes  of  fragments  of  crushed  stone,  from  two  inches 
in  size  down  to  dust  (which  form  about  nine-tenths  of 
the  final  mass),  are  accurately  determined  and  are  so 
combined  in  such  proportions  of  the  six  or  more  sizes 
that  the  final  voids  between  the  fragments  after  rolling 
do  not  exceed  ten  per  cent,  or  less  than  half  the  ordinary 
voids  in  rolled  stone.  This  puts  the  fragments  into 
actual  and  firm  contact,  so  that  the  addition  of  ten  to 
twelve  per  cent  by  weight  (twelve  to  sixteen  per  cent  by 
bulk)  of  bituminous  compound  fills  the  remaining  voids 
and  makes  a  solid  and  impervious  mass.  This  result 
requires  experienced  care  and  skill  in  selecting  and  com- 
bining the  best  materials,  including  testing  and  analyzing 
the  components  of  the  bituminous  cement.  The  pave- 
ment thus  produced  is  one  which  water  cannot  penetrate, 
and  it  supports  the  passage  of  heavy  and  high-speed 

127 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

vehicles  without  any  loosening  of  the  bituminous  filler 
and  without  abrasion  of  the  fragments  of  stone,  so  that 
no  dust  comes  from  the  pavement  or  its  materials. 


OPINIONS. 

With  the  present  general  knowledge  of  it  which  has 
been  acquired  since  1901,  opinions  are  now  of  less 
moment  than  in  its  first  years  of  use,  when  it  was 
strongly  commended  by  the  writer  and  others  who  were 
quoted,  in  the  1902  edition  of  "City  Roads  and  Pave- 
ments," and  again  in  the  1906  edition,  where  it  is  de- 
scribed in  detail.  One  of  the  best  and  most  weighty  of 
the  opinions  which  have  been  published  is  that  of  George 
W.  Tillson,  president  of  the  American  Society  of  Munic- 
ipal Improvements,  Chief  Engineer  of  the  Bureau  of 
Highways  of  the  Borough  of  Manhattan  (New  York 
City  proper),  and  author  of  the  standard  book,  "Street 
Pavements  and  Paving  Materials,"  who  said  before  the 
Franklin  Institute  in  1906: 

"Bitulithic  pavement  is  made  of  crushed  rock  and  bitumen,  the 
particles  of  stone  being  mixed  in  certain  scientifically  predetermined 
proportions  as  to  sizes,  so  as  to  provide  a  maximum  of  density  and 
a  minimum  of  voids,  so  that  the  resulting  bituminous  concrete  is 
nearly  as  dense  as  a  block  of  solid  stone  with  a  surface  that  offers 
as  little  resistance  to  traction  as  asphalt,  but  one  that  is  not  slippery, 
because  the  fine  stone  used  in  the  finishing  course  provides  a  gritty 
surface,  similar  to  macadam,  which  affords  secure  footing  for  horses 
at  all  seasons." 

In  November,  1907,  at  the  meeting  of  the  Massachu- 
setts Highway  Association  (see  page  13)  to  discuss  "sup- 
pression of  dust,1*  Franklin  C.  Pillsbury,  expressing  the 

128 


BITULITHIC  PAVEMENT. 

opinion  of  the  Massachusetts  Highway  Commission,  of 
which  he  is  division  engineer,  said: 

"The  bitulithic  pavement  is  undoubtedly  the  best  form  of  pave- 
ment to  give  the  desired  results  (durability  and  freedom  from  dust 
under  fast  motor-car  travel),  but  it  is  too  expensive  for  many  loca- 
tions." 

A  practical  expression  of  opinion  was  recently  given 
by  the  Chicago  South  Park  Commission,  which  selected 
it  for  use  on  several  miles  of  fifty-feet  boulevards  after 
two  weeks  of  investigation  and  after  competitive  bids  for 
other  forms  of  pavement. 


HISTORY. 

It  was  first  used  in  1901  in  Pawtucket,  R.  I.,  where 
it  was  laid  on  a  twelve  per  cent  grade  on  Harvey 
Street.  During  the  same  year  sample  areas  were  built 
in  seven  cities,  aggregating  about  one  mile  of  thirty- 
feet  width.  The  success  was  immediate,  and  the  use 
increased  each  succeeding  year,  so  that  at  the  close  of 
1907  six  and  one-half  million  square  yards,  equal  to 
422  miles  of  thirty-feet  roadways,  had  been  laid  in  one 
hundred  and  sixty-six  cities  of  the  United  States  and 
Canada,  including  cities  in  the  region  of  extreme  cold, 
as  at  Edmonton,  province  of  Alberta,  Northwest  Canada, 
and  Glace  Bay,  Nova  Scotia,  and  in  the  South  at  El  Paso, 
Texas,  and  at  Atlanta,  Georgia.  This  wide-spread 
success  has  induced  imitations  and  consequent  litiga- 
tions, which  are  further  evidences,  if  such  were  needed, 
of  the  merits  of  the  construction. 


129 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 


METHODS. 

The  base  for  bitulithic  pavement  is  varied  to  best  fit 
the  local  conditions.  On  gravelly  soil  which  can  be 
rolled  solid,  a  bituminous  base  can  be  used,  formed  of 
crushed  stone  or  slag  of  two  inches  to  three  inches  size, 
spread  to  a  uniform  depth  of  four  to  six  inches  and 


LAYING  BITULITHIC  PAVEMENT  ON  E.  MAIN  STREET,  SPARTANBURG,  S.  C. 
(See  larger  photograph  of  Flush-coat  Spreading  Machine  and  Stone- 
sprinkling  Machine  shown  in  background.) 

rolled,  dry,  with  heavy  steam-rollers.  This  is  followed 
by  a  coating  or  "binder"  of  hard,  waterproof,  bitu- 
minous cement.  On  soil  which  is  sandy,  or  which 
cannot  be  rolled  to  be  solid,  an  ordinary  six-inch  base 
of  hydraulic-cement  concrete  is  made,  with  the  addition 

130 


BITULITHIC  PAVEMENT. 

of  tamping  into  its  plastic  surface  fragments  of  crushed 
stone  in  order  to  make  it  rough.  On  a  formerly  paved 
street,  the  old  pavement  can  be  used  as  a  base  for  a 
bitulithic  surface. 

Upon  the  base  of  whichever  sort,  the  "wearing  sur- 
face" is  spread  and  while  still  hot  is  compressed  with 
heavy  rollers  to  a  finished  thickness  of  two  inches. 


FLUSH  COAT  SPREADING  MACHINE. 
(Patented.) 

Used  in  spreading  the  quick-drying 
bituminous  flush  coat  on  the  sur- 
face of  the  bitulithic  pavement. 


STONE- SPRINKLING   MACHINE 

(Patented). 

Used  in  sprinkling  hot  stone  chips  on 
the  surface  of  the  bitulithic  pave- 
ment, to  be  rolled  into  the  bitu- 
minous flush  coat. 


Proportions. — This  wearing  surface  is  formed  of  the 
best  and  toughest  available  crushed  rock,  varying  in  size 
from  a  maximum  of  one  and  one-half  inches  and  one  inch 
down  to  dust,  which  material  is  heated  and  dried  in 


131 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

rotary  drums  and  is  then  screened  in  rotary  screens, 
which  separate  it  into  six  or  more  sizes.  Tests  are  then 
made  to  determine  the  proper  proportions  of  the  different 
sizes  which  will  produce  the  densest  mixture  having  the 
smallest  percentage  of  voids.  These  tests  are  daily 
repeated  by  the  makers  during  the  progress  of  the 
work  upon  samples  taken  from  it,  in  order  to  have 
assurance  of  perfect  uniformity  in  the  pavement. 

Mixing. — The  determined  proportions  by  weight  of 
each  size  are  run  through  the  hopper  of  an  automatic 
weighing-machine,  into  a  mechanical  mixer,  at  a  tem- 
perature of  250°  F.,  and  are  there  combined  with  an 
accurately  weighed  proportion  of  heated  bituminous 
cement,  of  which  the  composition  is  the  result  of 
close  tests  and  which  is  carefully  determined  to  be  of  a 
sufficient  quantity  (but  not  too  much),  to  fill  all  final 
voids  by  coating  the  faces  of  all  particles  of  stone  and 
of  sand  and  of  dust,  and  also  providing  a  slight  surplus 
as  a  "  filler." 

Spreading  and  Rolling. — When  thus  mixed,  the  hot 
stone  and  bitumen  is  hauled  to  place  on  the  road,  and 
is  there  spread  and  rolled  while  hot,  using  a  twelve- 
ton  to  twenty-ton  steam-roller  to  assure  the  maximum 
compression  which  crowds  the  bitumen  into  all  the 
voids  and  forces  out  all  air-bubbles,  and  makes  the 
most  dense  surface  possible.  Upon  this  surface,  filling 
it  and  making  it  sticky,  there  is  then  poured  and  rubbed 
a  coating  of  quick-drying  bituminous  cement  heated 
to  250°  F.,  over  which  is  at  once  spread  a  quarter- 
inch  layer  of  small  stone  chips  which  are  rolled  into 
the  sticky  coating  and  form  a  final  wearing  surface, 
the  size  of  these  chips  being  larger  as  the  grade  is 
steeper. 

132 


Dismantled  ready  for  shipment. 


Set  up  ready  for  operation. 

ONE-CAR  PORTABLE  BITULITHTC  RAILROAD  PLANT.     (PATENTED). 

133 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

The  elaborate  outfit  of  laboratory  and  machinery  and 
skilled  direction  required  to  successfully  produce  this 
pavement  would  at  first  seem  to  limit  construction  to  the 
vicinity  of  permanent  plants,  and  this  idea  is  strengthened 
by  visiting  such  a  plant  and  examining  the  work  in  pro- 
gress. There  have,  however,  been  built  and  patented 
by  the  Warren  Brothers  Company,  of  Boston,  Massachu- 
setts, a  number  of  "  semi-portable  bitulithic  paving- 
plants,"  each  permanently  set  upon  a  platform-car,  of 
which  full  illustrations  showing  details  are  here  given. 
These  outfits  make  it  possible  to  build  this  pavement 
in  many  widely  distant  places  and  to  give  to  all  of  them 
equally  reliable  results.  The  six  illustrations  showing 
this  " semi-portable  bitulithic  paving-plant  (patented)" 
are  all  lettered  to  accord  with  the  following  key: 

A.  Boiler  and  engine. 

B.  Rotary  driers  for  heating  and  drying  stone. 

C.  Elevators  for  delivering  the  stone  to  the  driers. 

D.  Elevators    for  conveying  the  heated   stone    to    the   separating- 

screens. 

E.  Sectional  screen  for  separating  the  stone  into  several  sizes. 

F.  Sectional  bins  for  storing  the  several  sizes  of  stone  after  sepa- 

ration, and  delivering  same  to  the  weighing-box. 

G.  Weighing-box  resting  on  a  multiple  seven-beam  scale  for  accu- 

rately weighing  each  size  of  stone  in  predetermined  propor- 
tions and  delivering  same  into  the  mixer. 
H.  Twin  pug  mechanical  mixer,   having  two  shafts   revolving  in 

opposite   directions   with   arms   or  blades   interlocking  each 

other. 
I.   Mixing  platforms   under  which  wagons   back   for  taking  the 

bitulithic  mixture  as  delivered  from  the  mixer. 
J.    Ogee-bottomed  bitumen-melting  tanks. 
K.  Bitumen  weigh-bucket  conveyor  and  dial-scale,  so  arranged  as 

to  indicate  both  gross  weight  and  tare. 
L.  Rotary  exhaust  fan  for  providing  induced  draft  to  the  rotary 

driers. 

134 


END  VIEW. 


SIDE  VIEW. 

SEMI-PORTABLE  BITULITHIC  PAVING  PLANT.     (PATENTED). 

135 


ROAD  PRESERVATION  AND  DUST  PREVENTION. 

M.  Dust-separator  for  reclaiming  dust  drawn  by  the  exhaust  fan 
from  the  stone  while  it  is  drying. 

N.  Steel  frame  for  supporting  the  mixing-platform,  mixer,  scale, 
sectional  hot-stone  bin,  and  sectional  screens. 

O.  Steel  car  on  which  the  semi-portable  or  railroad  plant  is  per- 
manently set. 

Cost. — The  cost  of  bitulithic  pavement  varies  with  the 
local  prices  of  the  materials,  and  with  the  local  conditions. 
It  is  usually  $2  to  $2.50  per  square  yard,  exclusive  of 
grading  and  inclusive  of  guaranty.  This  high  cost  limits 
its  use  to  cities  and  parks,  and  prevents  general  use  on 
rural  roads. 


136 


INDEX. 


PAGE 

ASPHALTOILENE — (see  "Oil  on  roads;  Petroleum") 58 

ASSOCIATION — 

Massachusetts  Highway 8,  13 

Roads,  Improvement  of,  England 33,  35,  70 

BITULITHIC  PAVEMENT 16,  92, 100,  127-136 

Address 134 

Cost 136 

Composition 127 

Description 127 

Extent 129 

History , 129 

Methods — 

Base 130 

Wearing  Surface 131 

Proportions 131 

Mixing ;  .  .  .    132 

Rolling 132 

Spreading 132 

Testing 132 

Opinions 128 

Portable  Plant 134 

Summary 127 

BROKEN  STONE  ROADS — 

Calcium  Chloride  upon 18,  23 

Coal-tar  upon 16,  63,  65,  97 

Appliances 87 

Composition 86 

Cost 83,87 

History 69 

Spraying  machines 89 

Sprinkling  machine 88 

Destruction 11, 13, 15,    0 

Emulsions  upon 25.  jl 

Existence 10,  11 

Gladwell  system 15,  111 

Maintenance 11,  14 

New  Surface 82 

Oil  upon 37, 42-50 

Penetration 69,  84 

Sand  rock-asphalt  as  binder  for 126 

Tar  macadam 98 

Cost 9D,  102, 103, 107 

History 99 

Methods 101, 107 

Tarvia  upon 74 

Hot 76 

Cold 77 

137 


INDEX. 

PAGE 

CALCIUM  CHLORIDE 18-22 

Characteristics 19 

Cost 19 

Methods 19 

At  Beverley,  Mass 20 

Cost 20 

Good  Effects 21 

Improved 20 

At  Brookline,  Mass 22 

Conclusions 23 

CLARE'S  PATENT  TAR  COMPO 73 

COAL-TAR  ON  ROADS 10,  15,  16,  63-120 

Appliances 87 

Heating 63,87,  102,  120 

Steam  coils 64-94 

Spreading 88 

Spraying 69,  89-97 

Conditions  for  success 67 

Failures 68;  71 

History 69 

Objections •     67 

Opinions — 

Aitken,  Thomas 65 

French  engineers 65 

Mass.  Highway  Commission 65 

Page,  Logan  Waller 66 

Ross,  Charles  W 84 

Penetration 69,  84,  88 

Preparations 74 

Quality 71 

Ductility 63,  71 

Uniformity 64,  73 

Variations 72 

Spraying  machines 15,  69,  89-97 

Summary 63 

Tarvia 73,  74 

Address 73 

Commendations — 

Gladwell  system Ill 

Mass.  Highway  Com 73 

U.  S.  Office  Public  Roads 73 

Cold"B-"— 

Cost 78 

Spreading 77 

Results 78 

Hot  "A"— 

Cost 77 

Covering 77 

Heating 76 

Spreading 76 

Massachusetts  roads 79 

Boston  park  roads 80 

Cost 80 

Defects 81 

Lynn 81 

138 


INDEX. 

PAGE 

Coal- tar  on  roads — (Continued} — 

Cost 82 

Crust 81 

Methods 82 

Results :.. 82 

Newton — 

Cost 83 

Methods 83 

Results 84 

Wayland — 

New  surface 82 

Penetration 69,  84,  88 

Rhode  Island  roads — 
Tiverton — 

Costs 85 

Methods 84 

Results 85 

Steep  grade 85 

United  States  Office  of  Public  roads- 
Experiments — 

Composition 86 

Conclusions 87 

Methods 86 

CLUB — Royal  Automobile 70 

COMMISSION — Massachusetts  Highway 8, 11, 14 

Royal 15 

CONGRESS — International  roads 16 

DUST — Characteristics,  9;  Danger  from,  12;  Nuisance,  11,  12;  Pre- 
vention  7,  11 

EMULSIONS 24 

Apulvite 31 

Conclusions 34 

Coudrogenit 30 

Crempoid  D 32 

Dustoline 32 

Cost 32 

Effects 24-25 

Ermenite 33 

Hahnite 34 

Mechanical 35 

Cost 36 

Method 35 

Results 35 

Methods 25 

Boston  park  roads 25 

Conclusions 27 

Cost 26 

Effects 27 

Chicago  park  roads 27 

Cost 28 

Effects 28 

Objections 24 

Pine-oiline 31 

Pulvicide 33 

Rapidite 34 

139 


INDEX. 

PAGE 
Emulsions — (Continued') — 

Sandisize 31 

Cost 32 

Summary 24 

Terracolia 33 

Westrumite 29 

Characteristics 29 

Conclusions 34 

Cost 30-31 

Methods 

France 30 

Germany 30 

United  States 31 

Chicago 29 

Limitations 31 

St.  Paul 31 

EXPERIMENTS — Conclusions,   17;    England,    15;  France,   16;  United 

States,  16;  Chicago  parks , 27 

GAS  BY-PRODUCTS— (see  " Oil  on  roads") 60 

Coal-tar 10, 15,  16,  63-120 

Creosote  oil 43,  60,  62 

Oil-gas  tar 61,  62 

Oil-tar 60 

Tar-oil 60 

Water-gas  tar 35,  60,  86 

GLADWELL  SYSTEM 15,  111 

MACADAM  ROADS — (see  "Broken  stone  roads") — 

MOISTURE 18 

Atmospheric — 

Akonia 23 

Calcium  chloride 18-22 

Fitzsimmons  patent  dust  layer 23 

Lymanite 23 

Sea-water 18 

Crust  caused  by 81 

Water 18 

Cost  of 18,  21,  27,  43 

MOTOR-CARS,  EFFECTS  OF 7, 10, 13, 14, 16 

Race-track 14 

MOTOR  UNION 70 

OIL,  ON  ROADS 37 

Broken  stone  roads — 
Arkansas — 

Little  Rock 48 

Australia — 

Sidney 44 

Cost 44 

Results 44 

California 52,  56 

Pasadena 47 

England — 

Liverpool 43,  62 

Illinois — 

Chicago 48 

Massachusetts — 

140 


INDEX. 

PAGE 

Oil  on  roads — (Continued) — 

Beverley 49 

Precautions 49 

Newton 50 

New  York 50 

Cost 51 

Rhode  Island — 

Barrington 47 

Cost 47 

Results 48 

Cranston 42 

Cost 42 

Results 43 

Tennessee — 

Jackson 45 

Costs 46 

Heavy  Residual 46 

Light  crude 45 

Residual 45 

Clay  roads 51-55 

Earth  roads 52,  55 

Failures 24-41-57 

Gravel  roads 56 

Gas  by-products 60 

Composition 60,  86 

Conclusions 62 

Creosote  oil 43-60-62 

Odocreol 60 

Oil-gas  tar 61-62 

Oil-tar 60 

Tar-oil 60 

Water-gas  tar 35,  60 

Composition 61-86 

Methods 61 

Gulf  Refining  Company,  address 49 

Objections 40-41 

Petroleum 37 

By-products 38 

Distillation 38 

History 41 

Mazout 60 

Residuum 38 

Texas 57 

Kentucky 58 

Asphaltoilene 58 

Address 58 

Cost 58 

Extent 59 

Method 58-59 

Asphaltine 59 

Cost 60 

Sources — 

Borneo 38 

California — 

Adeline  wells 38 

141 


INDEX. 

PAGE 
Oil  on  roads — (Continued) — 

Asphaltic 41 

Characteristics 38 

History 41 

Methods — 

Clay 51-55 

Earth 32,  55 

Gravel 56 

Repairs 57 

Sand 41,  51,  52,  55 

Stone 47,  52-56 

Substitutes 52 

Galicia 38-42,  60 

Indian  Territory 38-42 

Kansas 28,  38-40-42,  52 

Kentucky 38-40-42,  58 

Louisiana 45 

Ohio 37-42 

Pennsylvania 37-42 

Russia 37-42,  60 

Texas 38-40,  43, 45, 47, 48,  49,  52,  57 

Tests 38 

Petrolithic  roads 16,  51,  52 

Address 54 

Cost 51,  54 

Method 51,  52 

Oiling 53 

Ploughing 53 

Roller 16-54 

Tamping 53 

Rural  roads — 

Cost 55 

Method 55 

Sand  roads 37,41,51,52,55 

California 16, 41-51-52-55 

Massachusetts 57 

Cost 58 

Method 58 

Frost  on 58 

Michigan 17 

Repairs 57 

Screenings  oiled — 

Cost 50 

Effects 50 

Standard  Oil  Company 42 

Address 50 

White  Sprinkler 51,  52,  76,  88 

Address 88 

PETROLITHIC  ROADS 16,  51,  52 

Address 54 

Cost 51,  54 

Method 51,  52 

Oiling 53 

Ploughing 53 

142 


INDEX. 

PAGE 

Petrolithic  roads — (Continued} — 

Roller 16,  54 

Tamping 53 

PETROLEUM — (see  " Oil  on  roads") — By-products,    38;    History,    41;' 
Residuum,  37,  57-60;  Sources,  38,  40,  52,  57;  Tests 38 

PREFACE 7 

REFERENCES — 

Adams,  Arthur  W 68 

Aitken,  Thomas 65,  89,  90 

Arnaud,  M 65 

Blanchard,  Arthur  W 48,  84,  117 

Bishop,  Cortlandt  F 14 

Brown,  Arthur 110 

Conley,  P.  J 42 

Ellery,  N 55,  56 

Fletcher,  A.  B 13 

Foster,  J.  F 30 

George-Powell,  J 108 

Gladwell,  Arthur 15 

Girardeau,  M 65,  69 

Heude,  M 65,  95 

Humphreys,  H.  Howard 115 

Manning,  Geo.  W 114 

McClintock,  Wm.  E 11 

Owen,  James 11 

Page,  Logan  Waller 11,  45,  85,  87,  116, 123 

Pettigrew,  John  A 26 

Pillsbury,  Franklin  C 20,  78,  128 

Poore,  H.  C 119,  120 

Rablin,  John  R 80 

Reichardt,  Walter  F 48,  122 

Rose,  John  Colin 44 

Ross,  Charles  W 50,  59,  83 

Sigault,  M 65 

Sohier,  Wm.  D 13,  49 

Tillson,  Geo.  W 128 

Vahheur,  M 65 

Whyatt,  H.  G 101 

Wike,  Charles  F 109 

Publications  referred  to 8 

ROCK-ASPHALT  MACADAM 121 

Methods- 
City  streets — 

Arkansas,  Little  Rock — 

Cost 123 

Result 123 

Rolling 123 

Spreading 122 

Suburban  roads — 

Kentucky,  Bowling  Green — 

Cost  "WTadsworth"  Macadam 125 

Description 123 

Results 125 

143 


INDEX. 

PAGE 
Rock-asphalt  macadam — (Continued} — 

Rolling 124 

Spreading 124 

Sand-rock  sheet  asphalt — 

Cost,  Methods 126 

Sand-rock  asphalt  for  macadam  binder 126 

Sources 121 

Summary 121 

ROLLING  TAMPER 16,  53,  54 

SURFACE — 

Perservation 7, 10, 41 

Treatments 58 

Calcium  chloride 18 

Coal-tar 63 

Emulsions 24 

Oils 37 

Water 18 

SLAG — Defects  in,  104;  Use  of 104 

TAR — (see  "coal-tar  on  roads") 

TARMAC,  address \ .    104 

Cost 106 

Extent 105 

History 104 

Objections 104 

Methods- 
Birmingham — 

Ettingshall 104 

Gainsborough 106 

Grimsby 106 

Newark 104 

Sheffield 105 

Slag,  defects  in 104 

TAR  MACADAM 82,  98, 120 

Canada — 

Hamilton — cost 117 

Ottawa — cost 117 

Toronto — cost 117 

England 82,  98, 115 

Crushed  stone — 

Cost,  comparative — 

Gainsborough 103 

Grimsby 101 

London 109, 110 

Manchester 108 

Northumberland 108 

Nottingham 102, 110 

Sheffield 103, 109 

Methods — 

Hand  labor 101 

Cost 102 

Machines 100, 102, 103 

Cost 102, 103 

Results 99,  108, 110 

Steep-grade 85,  110 

Gladwell  system 15,  98,  99,  111,  116 

144 


INDEX. 

PAGE 
Tar  macadam — (Continued) — 

Cost 114, 115 

History Ill 

Method 112 

Finishing 114 

Rolling : 113 

Spreading 112 

Tarring 112 

Thickness 114 

Opinions 115 

Cost,  Comparative 99 

Failures 110 

History 99 

Summary'. 115 

United  States— 

Massachusetts — 

Estimates 119 

Kettles 120 

Rhode  Island — 
Charlestown — 

Cost 118 

Methods 117 

Narragansett  Pier — 

Methods 118 

Varieties i  .  .  .  98 

TAR-PAINTING 72,  92,  98 

TAR-SPRAYING  MACHINES 15,  69,  89,  97 

Aitken's 89 

Address 89 

Cost 91 

Details 90 

Method 90 

Results 92 

Rolling 90 

Spraying — 

New  Macadam 90 

Cost  in  England 91 

Cost  in  United  States 91 

Old  Macadam 92 

Cost 93 

Conclusions 97 

Lassai  ly — Johnston 94 

Co  t 95 

Details 94 

Good  r  suits — 

In  England 95 

In  France 95 

Tarmaciser — 

Address 97 

Details 97 

Tarspra — 

Address , 93 

Details 93 

Number  in  use 93 

Results 93 

145 


INDEX. 

PAGE 
Tar-spraying  machines — (Continued} — 

Thwaite 96 

Cost 96 

Details 96 

TARVIA — (see  "Coal-tar  on  roads") 73,  74 

Commendations 73.  Ill 

Cold"B" 77 

Hot  "A" 76 

Massachusetts  roads 79 

WADSWORTH  Rock-asphalt  macadam 51,  125 

WESTRUMITE — (see   "Emulsions") 29 

WHITE  SPRINKLER 51,  52,  76, 78 


146 


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